WO2024167357A1 - Method for operating multipath-related ue in ue-to-ue relay in wireless communication system - Google Patents

Abstract

According to an embodiment, a method for operating a source remote user equipment (UE) in a UE-to-UE relay in a wireless communication system comprises steps in which the source remote UE: establishes a direct link with a target remote UE; establishes an end-to-end link, corresponding to an indirect link, with the target remote UE via a relay UE; activates at least one of the direct link or the indirect link; and transmits a message to the target remote UE via the activated link, wherein an upper layer of the source remote UE notifies an AS layer of both a first ID set, including a first SRC ID and a first DST ID used for the indirect link, and a second ID set, including a second SRC ID and a second DST ID related to the direct link.

Description

Method of operation of UE related to multipath in UE-TO-UE relay in wireless communication system

The following description relates to a wireless communication system, and more specifically, to an operation method and device of a source remote UE, etc., related to multipath in a UE-to-UE relay.

In wireless communication systems, various RATs (Radio Access Technologies), such as LTE, LTE-A, and WiFi, are used, and 5G is also included. The three major requirement areas of 5G are (1) Enhanced Mobile Broadband (eMBB), (2) Massive Machine Type Communication (mMTC), and (3) Ultra-reliable and Low Latency Communications (URLLC). Some use cases may require multiple areas for optimization, while other use cases may focus on only one Key Performance Indicator (KPI). 5G supports these various use cases in a flexible and reliable manner.

eMBB goes far beyond basic mobile Internet access, covering rich interactive tasks, media and entertainment applications in the cloud or augmented reality. Data is one of the key drivers of 5G, and for the first time in the 5G era, we may not see dedicated voice services. In 5G, voice is expected to be handled as an application simply using the data connection provided by the communication system. The main reasons for the increased traffic volume are the increase in content size and the increase in the number of applications requiring high data rates. Streaming services (audio and video), interactive video and mobile Internet connectivity will become more prevalent as more devices are connected to the Internet. Many of these applications require always-on connectivity to push real-time information and notifications to users. Cloud storage and applications are rapidly growing on mobile communication platforms, and this can be applied to both work and entertainment. And cloud storage is a particular use case that is driving the growth of uplink data rates. 5G is also used for remote work in the cloud, requiring much lower end-to-end latency to maintain a good user experience when tactile interfaces are used. Entertainment For example, cloud gaming and video streaming are other key factors driving the demand for mobile broadband capabilities. Entertainment is essential on smartphones and tablets anywhere, including in high-mobility environments such as trains, cars, and airplanes. Another use case is augmented reality and information retrieval for entertainment. Here, augmented reality requires very low latency and instantaneous data volumes.

Also, one of the most anticipated 5G use cases is mMTC, the ability to seamlessly connect embedded sensors across all sectors. It is predicted that there will be 20.4 billion potential IoT devices by 2020. Industrial IoT is one area where 5G will play a key role in enabling smart cities, asset tracking, smart utilities, agriculture, and security infrastructure.

URLLC encompasses new services that will transform industries through ultra-reliable/available low-latency links, such as remote control of critical infrastructure and self-driving vehicles. Reliability and latency levels are essential for smart grid control, industrial automation, robotics, and drone control and coordination.

Next, let's look at a number of use cases in more detail.

5G can complement fiber-to-the-home (FTTH) and cable-based broadband (or DOCSIS) by delivering streams rated at hundreds of megabits per second to gigabits per second. These high speeds are required to deliver television at resolutions of 4K and beyond (6K, 8K and beyond), as well as virtual and augmented reality. Virtual Reality (VR) and Augmented Reality (AR) applications include near-immersive sporting events. Certain applications may require special network configurations. For example, VR gaming may require gaming companies to integrate their core servers with the network operator’s edge network servers to minimize latency.

Automotive is expected to be a major new driver for 5G, with many use cases for mobile communications in vehicles. For example, entertainment for passengers requires simultaneous high-capacity and high-mobility mobile broadband, as future users will continue to expect high-quality connectivity regardless of their location and speed. Another application in the automotive sector is an augmented reality dashboard, which displays information superimposed on what the driver sees through the windshield, identifying objects in the dark and telling the driver about their distance and movement. In the future, wireless modules will enable communication between vehicles, information exchange between vehicles and supporting infrastructure, and information exchange between vehicles and other connected devices (e.g. devices accompanied by pedestrians). Safety systems can guide drivers to alternative courses of action to drive more safely, thus reducing the risk of accidents. The next step will be remotely controlled or self-driven vehicles, which will require highly reliable and very fast communication between different self-driving vehicles and between vehicles and infrastructure. In the future, self-driving cars will perform all driving activities, leaving drivers to focus only on traffic anomalies that the car itself cannot identify. The technical requirements for self-driving cars will require ultra-low latency and ultra-high reliability to increase traffic safety to levels that humans cannot achieve.

Smart cities and smart homes, referred to as smart societies, will be embedded with dense wireless sensor networks. A distributed network of intelligent sensors will identify conditions for cost- and energy-efficient maintenance of a city or home. A similar setup can be done for each home. Temperature sensors, window and heating controllers, burglar alarms, and appliances are all connected wirelessly. Many of these sensors are typically low data rates, low power, and low cost. However, for example, real-time HD video may be required for certain types of devices for surveillance.

The consumption and distribution of energy, including heat or gas, is becoming highly decentralized, requiring automated control of distributed sensor networks. Smart grids interconnect these sensors using digital information and communication technologies to collect information and act on it. This information can include the actions of suppliers and consumers, allowing smart grids to improve efficiency, reliability, economy, sustainability of production, and distribution of fuels such as electricity in an automated manner. Smart grids can also be viewed as another sensor network with low latency.

The health sector has many applications that can benefit from mobile communications. Telecommunication systems can support telemedicine, which provides clinical care from a distance. This can help reduce distance barriers and improve access to health services that are not always available in remote rural areas. It can also be used to save lives in critical care and emergency situations. Mobile-based wireless sensor networks can provide remote monitoring and sensors for parameters such as heart rate and blood pressure.

Wireless and mobile communications are becoming increasingly important in industrial applications. Wiring is expensive to install and maintain. Therefore, the possibility of replacing cables with reconfigurable wireless links is an attractive opportunity for many industries. However, achieving this requires that wireless connections operate with similar delay, reliability and capacity as cables, and that their management is simplified. Low latency and very low error probability are the new requirements that need to be connected with 5G.

Logistics and freight tracking are important use cases for mobile communications, enabling tracking of inventory and packages from anywhere using location-based information systems. Logistics and freight tracking use cases typically require low data rates but require wide range and reliable location information.

A wireless communication system is a multiple access system that supports communication with multiple users by sharing available system resources (e.g., bandwidth, transmission power, etc.). Examples of multiple access systems include a CDMA (code division multiple access) system, an FDMA (frequency division multiple access) system, a TDMA (time division multiple access) system, an OFDMA (orthogonal frequency division multiple access) system, an SC-FDMA (single carrier frequency division multiple access) system, and an MC-FDMA (multi carrier frequency division multiple access) system.

Sidelink (SL) refers to a communication method that establishes a direct link between user equipment (UE) to directly exchange voice or data between terminals without going through a base station (BS). SL is being considered as a solution to address the burden on base stations due to rapidly increasing data traffic.

V2X (vehicle-to-everything) refers to a communication technology that exchanges information with other vehicles, pedestrians, and objects with built-in infrastructure through wired/wireless communication. V2X can be divided into four types: V2V (vehicle-to-vehicle), V2I (vehicle-to-infrastructure), V2N (vehicle-to-network), and V2P (vehicle-to-pedestrian). V2X communication can be provided through the PC5 interface and/or the Uu interface.

Meanwhile, as more and more communication devices require greater communication capacity, there is a growing need for improved mobile broadband communication over existing Radio Access Technology (RAT). Accordingly, communication systems that consider services or terminals sensitive to reliability and latency are being discussed, and the next-generation radio access technology that considers improved mobile broadband communication, massive MTC (Machine Type Communication), URLLC (Ultra-Reliable and Low Latency Communication), etc. can be called new RAT (new radio access technology) or NR (new radio). V2X (vehicle-to-everything) communication can also be supported in NR.

Figure 1 is a diagram for explaining and comparing V2X communication based on RAT prior to NR and V2X communication based on NR.

In relation to V2X communication, in RATs prior to NR, methods for providing safety services based on V2X messages such as BSM (Basic Safety Message), CAM (Cooperative Awareness Message), and DENM (Decentralized Environmental Notification Message) have been mainly discussed. V2X messages may include location information, dynamic information, attribute information, etc. For example, a terminal may transmit a CAM of a periodic message type and/or a DENM of an event triggered message type to another terminal.

For example, CAM may include basic vehicle information such as vehicle dynamic status information such as direction and speed, vehicle static data such as dimensions, exterior lighting status, and route history. For example, the terminal may broadcast CAM, and the latency of the CAM may be less than 100ms. For example, when an emergency situation such as a vehicle breakdown or an accident occurs, the terminal may generate DENM and transmit it to other terminals. For example, all vehicles within the transmission range of the terminal may receive CAM and/or DENM. In this case, DENM may have a higher priority than CAM.

Since then, various V2X scenarios have been proposed in NR in relation to V2X communication. For example, various V2X scenarios may include vehicle platooning, advanced driving, extended sensors, and remote driving.

For example, based on vehicle platooning, vehicles can dynamically form a group and move together. For example, in order to perform platoon operations based on vehicle platooning, vehicles belonging to the group can receive periodic data from the lead vehicle. For example, vehicles belonging to the group can use the periodic data to reduce or increase the gap between vehicles.

For example, based on improved driving, the vehicles can be semi-autonomous or fully automated. For example, each vehicle can adjust its trajectories or maneuvers based on data acquired from local sensors of nearby vehicles and/or nearby logical entities. Also, for example, each vehicle can share driving intentions with nearby vehicles.

For example, based on the extended sensors, raw data or processed data, or live video data acquired through local sensors can be exchanged between vehicles, logical entities, pedestrian terminals, and/or V2X application servers. Thus, for example, the vehicle can perceive the environment better than it can perceive using its own sensors.

For example, based on remote driving, for a person who cannot drive or a remote vehicle located in a dangerous environment, a remote driver or V2X application can operate or control the remote vehicle. For example, in the case of predictable paths such as public transportation, cloud computing-based driving can be used to operate or control the remote vehicle. In addition, for example, access to a cloud-based back-end service platform can be considered for remote driving.

Meanwhile, a method to specify service requirements for various V2X scenarios, such as vehicle platooning, enhanced driving, expanded sensors, and remote driving, is being discussed in NR-based V2X communications.

The present disclosure addresses a technical problem of an operation method and device of a source remote UE involved in multipath in a UE-to-UE relay.

One embodiment is a method for operating a source remote UE (User Equipment) in a UE-to-UE relay in a wireless communication system, the method including: the source remote UE establishing a direct link with a target remote UE; the source remote UE establishing an end-to-end link, corresponding to an indirect link, with the target remote UE through a relay UE; the source remote UE activating at least one of the direct link and the indirect link; and the source remote UE transmitting a message to the target remote UE through the activated link, wherein an upper layer of the source remote UE notifies an AS layer of a first ID set including a first SRC ID and a first DST ID used for the indirect link together with a second ID set including a second SRC ID and a second DST ID related to the direct link.

One embodiment is a wireless communication system, wherein a source remote UE in a UE-to-UE relay comprises at least one processor; and at least one computer memory operably connected to the at least one processor and storing instructions that, when executed, cause the at least one processor to perform operations, the operations comprising: establishing a direct link with a target remote UE; establishing an end-to-end link with the target remote UE, via the relay UE, corresponding to an indirect link; activating at least one of the direct link and the indirect link; and transmitting a message to the target remote UE via the activated link, wherein an upper layer of the source remote UE notifies an AS layer of a first set of IDs including a first SRC ID and a first DST ID used for the indirect link together with a second set of IDs including a second SRC ID and a second DST ID associated with the direct link.

One embodiment is a non-volatile computer-readable storage medium storing at least one computer program comprising instructions that, when executed by at least one processor, cause the at least one processor to perform operations for a source remote UE, the operations comprising: establishing a direct link with a target remote UE; establishing an end-to-end link with the target remote UE, via a relay UE, the end-to-end link corresponding to an indirect link; activating at least one of the direct link and the indirect link; and transmitting a message to the target remote UE via the activated link, wherein an upper layer of the source remote UE notifies an AS layer of a first set of IDs including a first SRC ID, a first DST ID used for the indirect link, together with a second set of IDs including a second SRC ID, a second DST ID associated with the direct link.

The above source remote UE may consider the indirect link corresponding to the first ID set and the direct link corresponding to the second ID set as links connected to the same target remote UE.

Activation of at least one of the above direct link and indirect link can be performed based on RSRP (Reference Signals Received Power).

The above direct link and indirect link may be allowed to be activated simultaneously regardless of the primary RLC entity.

The method may further include: the source remote UE selecting the relay UE associated with the addition of the indirect link; and the source remote UE establishing an SL connection with the relay UE.

The above source remote UE can consider that multi-path is established based on receiving a response to RRCReconfigurationSidelink transmitted through the indirect link through the direct link.

Based on the RSRP threshold of the bearer related to the direct path and the bearer related to the indirect path being equal to or greater than a reference value, the source remote UE can arbitrarily deactivate either an RLC entity existing in the direct path or an RLC entity existing in the indirect path.

The above RSRP threshold value may be determined by a higher layer of the source remote UE.

The threshold for the above indirect path and the threshold for the direct path may be different.

Based on the RSRP threshold of the bearer related to the direct path and the bearer related to the indirect path being less than or equal to a reference value, the source remote UE can transmit a message through both the RLC entity existing in the direct path and the RLC entity existing in the indirect path.

Based on whether either the signal strength of the direct path or the signal strength of the indirect path is less than or equal to the RSRP threshold, the source remote UE can transmit a message through a path whose signal strength is greater than or equal to the RSRP threshold.

In one embodiment, multi-path operation is possible in U2U operation according to the above embodiment. In addition, efficient path activation/deactivation is possible when PDCP duplication is allowed. By increasing data reliability and transmitting packets using only one path when channel conditions are good, transmission resources can be used dynamically and efficiently.

The drawings attached to this specification are intended to provide an understanding of the embodiments and to illustrate various embodiments and, together with the description of the specification, to explain the principles.

Figure 1 is a diagram for explaining and comparing V2X communication based on RAT prior to NR and V2X communication based on NR.

FIG. 2 illustrates the structure of an LTE system according to one embodiment of the present disclosure.

FIG. 3 illustrates a radio protocol architecture for a user plane and a control plane according to an embodiment of the present disclosure.

FIG. 4 illustrates the structure of an NR system according to one embodiment of the present disclosure.

FIG. 5 illustrates a functional partition between NG-RAN and 5GC according to one embodiment of the present disclosure.

Figure 6 shows the structure of a radio frame of NR to which the embodiment(s) can be applied.

FIG. 7 illustrates a slot structure of an NR frame according to one embodiment of the present disclosure.

FIG. 8 illustrates a radio protocol architecture for SL communication according to one embodiment of the present disclosure.

FIG. 9 illustrates a radio protocol architecture for SL communication according to one embodiment of the present disclosure.

FIG. 10 illustrates a synchronization source or synchronization reference of V2X according to one embodiment of the present disclosure.

FIG. 11 illustrates a procedure for a terminal to perform V2X or SL communication depending on a transmission mode according to one embodiment of the present disclosure.

FIG. 12 illustrates a procedure for a terminal to perform path switching according to one embodiment of the present disclosure.

Figure 13 illustrates a direct to indirect path transition.

Figures 14 and 15 are diagrams for explaining UE-to-UE Relay Selection.

Figure 16 illustrates a protocol stack in a UE-to-UE relay.

Figure 17 is a diagram related to packet duplication.

Figures 18 to 22 are drawings for explaining one embodiment.

Figures 23 to 29 illustrate various devices to which the embodiments can be applied.

In various embodiments of the present disclosure, “/” and “,” should be interpreted as representing “and/or”. For example, “A/B” can mean “A and/or B”. Furthermore, “A, B” can mean “A and/or B”. Furthermore, “A/B/C” can mean “at least one of A, B, and/or C”. Furthermore, “A, B, C” can mean “at least one of A, B, and/or C”.

In various embodiments of the present disclosure, “or” should be interpreted as meaning “and/or.” For example, “A or B” can include “only A,” “only B,” and/or “both A and B.” In other words, “or” should be interpreted as meaning “additionally or alternatively.”

The following technology can be used in various wireless communication systems, such as CDMA (code division multiple access), FDMA (frequency division multiple access), TDMA (time division multiple access), OFDMA (orthogonal frequency division multiple access), and SC-FDMA (single carrier frequency division multiple access). CDMA can be implemented with wireless technologies such as UTRA (universal terrestrial radio access) or CDMA2000. TDMA can be implemented with wireless technologies such as GSM (global system for mobile communications)/GPRS (general packet radio service)/EDGE (enhanced data rates for GSM evolution). OFDMA can be implemented with wireless technologies such as IEEE (institute of electrical and electronics engineers) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, E-UTRA (evolved UTRA). IEEE 802.16m is an evolution of IEEE 802.16e, providing backward compatibility with systems based on IEEE 802.16e. UTRA is part of UMTS (universal mobile telecommunications system). 3GPP (3rd generation partnership project) LTE (long term evolution) is a part of E-UMTS (evolved UMTS) that uses E-UTRA (evolved-UMTS terrestrial radio access), employing OFDMA in the downlink and SC-FDMA in the uplink. LTE-A (advanced) is an evolution of 3GPP LTE.

5G NR is a new clean-slate type mobile communication system that is the successor technology to LTE-A and has the characteristics of high performance, low latency, and high availability. 5G NR can utilize all available spectrum resources, from low frequency bands below 1 GHz to intermediate frequency bands between 1 GHz and 10 GHz, and high frequency (millimeter wave) bands above 24 GHz.

For clarity of explanation, the description will focus on LTE-A or 5G NR, but the technical ideas according to one embodiment of the present disclosure are not limited thereto.

FIG. 2 illustrates the structure of an LTE system according to one embodiment of the present disclosure. This may be called an Evolved-UMTS Terrestrial Radio Access Network (E-UTRAN), or a Long Term Evolution (LTE)/LTE-A system.

Referring to FIG. 2, the E-UTRAN includes a base station (20) that provides a control plane and a user plane to a terminal (10). The terminal (10) may be fixed or mobile, and may be called by other terms such as a mobile station (MS), a user terminal (UT), a subscriber station (SS), a mobile terminal (MT), a wireless device, etc. The base station (20) refers to a fixed station that communicates with the terminal (10), and may be called by other terms such as an evolved-NodeB (eNB), a base transceiver system (BTS), an access point, etc.

Base stations (20) can be connected to each other through the X2 interface. The base station (20) is connected to an EPC (Evolved Packet Core, 30) through the S1 interface, more specifically, to an MME (Mobility Management Entity) through the S1-MME and to an S-GW (Serving Gateway) through the S1-U.

EPC (30) consists of MME, S-GW, and P-GW (Packet Data Network-Gateway). MME has terminal connection information or terminal capability information, and this information is mainly used for terminal mobility management. S-GW is a gateway with E-UTRAN as an end point, and P-GW is a gateway with PDN (Packet Data Network) as an end point.

The layers of the Radio Interface Protocol between the terminal and the network can be divided into L1 (the first layer), L2 (the second layer), and L3 (the third layer) based on the three lower layers of the Open System Interconnection (OSI) standard model, which is widely known in communication systems. Among these, the physical layer belonging to the first layer provides an information transfer service using a physical channel, and the RRC (Radio Resource Control) layer located in the third layer controls radio resources between the terminal and the network. To this end, the RRC layer exchanges RRC messages between the terminal and the base station.

FIG. 3(a) illustrates a radio protocol architecture for a user plane according to an embodiment of the present disclosure.

FIG. 3(b) illustrates a wireless protocol structure for a control plane according to an embodiment of the present disclosure. The user plane is a protocol stack for transmitting user data, and the control plane is a protocol stack for transmitting control signals.

Referring to Figure 3(a) and A3, the physical layer provides information transmission services to the upper layer using a physical channel. The physical layer is connected to the upper layer, the Medium Access Control (MAC) layer, through a transport channel. Data moves between the MAC layer and the physical layer through the transport channel. The transport channel is classified according to how and with what characteristics data is transmitted through the wireless interface.

Data is transferred between different physical layers, that is, between the physical layers of the transmitter and receiver, through a physical channel. The physical channel can be modulated using the OFDM (Orthogonal Frequency Division Multiplexing) method and utilizes time and frequency as radio resources.

The MAC layer provides services to the upper layer, the radio link control (RLC) layer, through logical channels. The MAC layer provides a mapping function from multiple logical channels to multiple transport channels. In addition, the MAC layer provides a logical channel multiplexing function by mapping from multiple logical channels to a single transport channel. The MAC sublayer provides data transmission services on logical channels.

The RLC layer performs concatenation, segmentation, and reassembly of RLC SDUs (Serving Data Units). In order to guarantee various QoS (Quality of Service) required by Radio Bearers (RBs), the RLC layer provides three operation modes: Transparent Mode (TM), Unacknowledged Mode (UM), and Acknowledged Mode (AM). AM RLC provides error correction through automatic repeat request (ARQ).

The RRC (Radio Resource Control) layer is defined only in the control plane. The RRC layer is responsible for controlling logical channels, transport channels, and physical channels in relation to the configuration, re-configuration, and release of radio bearers. RB refers to a logical path provided by the first layer (physical layer or PHY layer) and the second layer (MAC layer, RLC layer, PDCP (Packet Data Convergence Protocol) layer) for data transmission between the terminal and the network.

The functions of the PDCP layer in the user plane include forwarding of user data, header compression, and ciphering. The functions of the PDCP layer in the control plane include forwarding of control plane data and ciphering/integrity protection.

Establishing an RB means the process of specifying the characteristics of the radio protocol layer and channel to provide a specific service, and setting each specific parameter and operation method. RB can be divided into two types: SRB (Signaling Radio Bearer) and DRB (Data Radio Bearer). SRB is used as a channel to transmit RRC messages in the control plane, and DRB is used as a channel to transmit user data in the user plane.

When an RRC connection is established between the RRC layer of the terminal and the RRC layer of the E-UTRAN, the terminal is in the RRC_CONNECTED state, otherwise it is in the RRC_IDLE state. For NR, an RRC_INACTIVE state is additionally defined, and a terminal in the RRC_INACTIVE state can release the connection with the base station while maintaining the connection with the core network.

Downlink transmission channels that transmit data from a network to a terminal include the BCH (Broadcast Channel) that transmits system information, and the downlink SCH (Shared Channel) that transmits user traffic or control messages. Traffic or control messages of downlink multicast or broadcast services may be transmitted through the downlink SCH, or may be transmitted through a separate downlink MCH (Multicast Channel). Meanwhile, uplink transmission channels that transmit data from a terminal to a network include the RACH (Random Access Channel) that transmits initial control messages, and the uplink SCH (Shared Channel) that transmits user traffic or control messages.

Logical channels that are located above the transport channel and are mapped to the transport channel include the Broadcast Control Channel (BCCH), Paging Control Channel (PCCH), Common Control Channel (CCCH), Multicast Control Channel (MCCH), and Multicast Traffic Channel (MTCH).

A physical channel consists of multiple OFDM symbols in the time domain and multiple sub-carriers in the frequency domain. One sub-frame consists of multiple OFDM symbols in the time domain. A resource block is a resource allocation unit and consists of multiple OFDM symbols and multiple sub-carriers. In addition, each subframe can use specific sub-carriers of specific OFDM symbols (e.g., the first OFDM symbol) of the corresponding subframe for the Physical Downlink Control Channel (PDCCH), i.e., the L1/L2 control channel. A Transmission Time Interval (TTI) is a unit time of subframe transmission.

FIG. 4 illustrates the structure of an NR system according to one embodiment of the present disclosure.

Referring to FIG. 4, the NG-RAN (Next Generation - Radio Access Network) may include a gNB (next generation-Node B) and/or eNB that provide user plane and control plane protocol termination to the UE. FIG. 4 exemplifies a case including only a gNB. The gNB and the eNB are connected to each other via an Xn interface. The gNB and the eNB are connected to a 5th generation core network (5G Core Network: 5GC) via an NG interface. More specifically, they are connected to an access and mobility management function (AMF) via an NG-C interface, and to a user plane function (UPF) via an NG-U interface.

FIG. 5 illustrates a functional partition between NG-RAN and 5GC according to one embodiment of the present disclosure.

Referring to FIG. 5, the gNB can provide functions such as inter-cell radio resource management (Inter Cell RRM), radio bearer management (RB control), connection mobility control (Connection Mobility Control), radio admission control (Radio Admission Control), measurement configuration & provision, and dynamic resource allocation. The AMF can provide functions such as NAS (Non Access Stratum) security and idle state mobility processing. The UPF can provide functions such as mobility anchoring and PDU (Protocol Data Unit) processing. The SMF (Session Management Function) can provide functions such as terminal IP (Internet Protocol) address allocation and PDU session control.

Figure 6 shows the structure of a radio frame of NR to which the embodiment(s) can be applied.

Referring to FIG. 6, a radio frame can be used in uplink and downlink transmission in NR. A radio frame has a length of 10 ms and can be defined as two 5 ms half-frames (Half-Frames, HF). A half-frame can include five 1 ms subframes (Subframes, SF). A subframe can be divided into one or more slots, and the number of slots in a subframe can be determined according to the subcarrier spacing (SCS). Each slot can include 12 or 14 OFDM (A) symbols according to the cyclic prefix (CP).

When normal CP is used, each slot can contain 14 symbols. When extended CP is used, each slot can contain 12 symbols. Here, the symbols can contain OFDM symbols (or CP-OFDM symbols), SC-FDMA symbols (or DFT-s-OFDM symbols).

Table 1 below shows the number of symbols per slot (μ) depending on the SCS setting (μ) when normal CP is used.

), number of slots per frame (

) and the number of slots per subframe (

) is an example.

Table 2 illustrates the number of symbols per slot, the number of slots per frame, and the number of slots per subframe according to SCS when extended CP is used.

In an NR system, OFDM(A) numerology (e.g., SCS, CP length, etc.) may be set differently between multiple cells that are merged into one terminal. Accordingly, the (absolute time) section of a time resource (e.g., subframe, slot, or TTI) (conveniently, collectively called TU (Time Unit)) consisting of the same number of symbols may be set differently between the merged cells.

In NR, multiple numerologies or SCS can be supported to support various 5G services. For example, when the SCS is 15 kHz, wide area in traditional cellular bands can be supported, and when the SCS is 30 kHz/60 kHz, dense-urban, lower latency and wider carrier bandwidth can be supported. When the SCS is 60 kHz or higher, a bandwidth greater than 24.25 GHz can be supported to overcome phase noise.

The NR frequency band can be defined by two types of frequency ranges. The two types of frequency ranges can be FR1 and FR2. The numerical value of the frequency range can be changed, and for example, the two types of frequency ranges can be as shown in Table 3 below. Among the frequency ranges used in the NR system, FR1 can mean “sub 6GHz range”, and FR2 can mean “above 6GHz range” and can be called millimeter wave (mmW).

As described above, the numerical value of the frequency range of the NR system can be changed. For example, FR1 can include a band of 410 MHz to 7125 MHz as shown in Table 4 below. That is, FR1 can include a frequency band of 6 GHz (or 5850, 5900, 5925 MHz, etc.) or higher. For example, the frequency band of 6 GHz (or 5850, 5900, 5925 MHz, etc.) or higher included in FR1 can include an unlicensed band. The unlicensed band can be used for various purposes, for example, it can be used for communication for vehicles (e.g., autonomous driving).

FIG. 7 illustrates a slot structure of an NR frame according to one embodiment of the present disclosure.

Referring to Fig. 7, a slot includes multiple symbols in the time domain. For example, in the case of a normal CP, one slot may include 14 symbols, but in the case of an extended CP, one slot may include 12 symbols. Or, in the case of a normal CP, one slot may include 7 symbols, but in the case of an extended CP, one slot may include 6 symbols.

A carrier includes a plurality of subcarriers in the frequency domain. An RB (Resource Block) can be defined as a plurality (for example, 12) of consecutive subcarriers in the frequency domain. A BWP (Bandwidth Part) can be defined as a plurality of consecutive (P)RBs ((Physical) Resource Blocks) in the frequency domain and can correspond to one numerology (for example, SCS, CP length, etc.). A carrier can include at most N (for example, 5) BWPs. Data communication can be performed through activated BWPs. Each element can be referred to as a Resource Element (RE) in the resource grid, and one complex symbol can be mapped.

Meanwhile, the wireless interface between terminals or between terminals and a network may be composed of an L1 layer, an L2 layer, and an L3 layer. In various embodiments of the present disclosure, the L1 layer may mean a physical layer. In addition, for example, the L2 layer may mean at least one of a MAC layer, an RLC layer, a PDCP layer, and an SDAP layer. In addition, for example, the L3 layer may mean an RRC layer.

Below, V2X or SL (sidelink) communication is explained.

FIG. 8 illustrates a radio protocol architecture for SL communication according to an embodiment of the present disclosure. Specifically, (a) of FIG. 8 illustrates a user plane protocol stack of LTE, and (b) of FIG. 8 illustrates a control plane protocol stack of LTE.

FIG. 9 illustrates a radio protocol architecture for SL communication according to an embodiment of the present disclosure. Specifically, (a) of FIG. 9 illustrates a user plane protocol stack of NR, and (b) of FIG. 9 illustrates a control plane protocol stack of NR.

FIG. 10 illustrates a synchronization source or synchronization reference of V2X according to one embodiment of the present disclosure.

Referring to Fig. 10, in V2X, a terminal can be directly synchronized to GNSS (global navigation satellite systems), or can be indirectly synchronized to GNSS through a terminal (within network coverage or out of network coverage) that is directly synchronized to GNSS. When GNSS is set as a synchronization source, the terminal can calculate the DFN and subframe number using UTC (Coordinated Universal Time) and a (pre-)configured DFN offset.

Alternatively, the terminal may be directly synchronized to the base station, or may be synchronized to another terminal that is time/frequency synchronized to the base station. For example, the base station may be an eNB or a gNB. For example, when the terminal is within network coverage, the terminal may receive synchronization information provided by the base station and be directly synchronized to the base station. Thereafter, the terminal may provide the synchronization information to other adjacent terminals. When the base station timing is set as the synchronization criterion, the terminal may follow the cell associated with the frequency (if it is within cell coverage at the frequency), the primary cell, or the serving cell (if it is outside cell coverage at the frequency) for synchronization and downlink measurement.

A base station (e.g., a serving cell) may provide synchronization settings for a carrier used for V2X or SL communication. In this case, the terminal may follow the synchronization settings received from the base station. If the terminal does not detect any cell on the carrier used for the V2X or SL communication and does not receive synchronization settings from the serving cell, the terminal may follow the preset synchronization settings.

Alternatively, the terminal may be synchronized to another terminal that has not obtained synchronization information directly or indirectly from the base station or GNSS. The synchronization source and preference may be preset for the terminal. Alternatively, the synchronization source and preference may be set via a control message provided by the base station.

SL synchronization source can be associated with a synchronization priority. For example, the relationship between synchronization source and synchronization priority can be defined as in Table 5 or Table 6. Table 5 or Table 6 is only an example, and the relationship between synchronization source and synchronization priority can be defined in various forms.

In Table 5 or Table 6, P0 may mean the highest priority, and P6 may mean the lowest priority. In Table 5 or Table 6, the base station may include at least one of a gNB or an eNB.

Whether GNSS-based synchronization or base station-based synchronization is used can be (pre-)configured. In single-carrier operation, the terminal can derive its transmission timing from the available synchronization reference with the highest priority.

Below, the SL synchronization signal (Sidelink Synchronization Signal, SLSS) and synchronization information are described.

SLSS is an SL-specific sequence and may include a Primary Sidelink Synchronization Signal (PSSS) and a Secondary Sidelink Synchronization Signal (SSSS). The PSSS may be referred to as a Sidelink Primary Synchronization Signal (S-PSS), and the SSSS may be referred to as a Sidelink Secondary Synchronization Signal (S-SSS). For example, length-127 M-sequences may be used for the S-PSS, and length-127 Gold sequences may be used for the S-SSS. For example, a terminal may detect an initial signal (signal detection) and acquire synchronization using the S-PSS. For example, the terminal may acquire detailed synchronization and detect a synchronization signal ID using the S-PSS and the S-SSS.

PSBCH (Physical Sidelink Broadcast Channel) may be a (broadcast) channel through which basic (system) information that a terminal must know first before transmitting and receiving an SL signal is transmitted. For example, the basic information may be information related to SLSS, duplex mode (DM), TDD UL/DL (Time Division Duplex Uplink/Downlink) configuration, resource pool related information, type of application related to SLSS, subframe offset, broadcast information, etc. For example, in order to evaluate PSBCH performance, in NR V2X, the payload size of PSBCH may be 56 bits including a 24-bit CRC.

The S-PSS, S-SSS and PSBCH may be included in a block format supporting periodic transmission (e.g., SL SS (Synchronization Signal)/PSBCH block, hereinafter referred to as S-SSB (Sidelink-Synchronization Signal Block)). The S-SSB may have the same numerology (i.e., SCS and CP length) as the PSCCH (Physical Sidelink Control Channel)/PSSCH (Physical Sidelink Shared Channel) in a carrier, and the transmission bandwidth may be within a (pre-)configured SL BWP (Sidelink BWP). For example, the bandwidth of the S-SSB may be 11 RB (Resource Block). For example, the PSBCH may span 11 RBs. And, the frequency location of the S-SSB may be (pre-)configured. Therefore, the terminal does not need to perform hypothesis detection in frequency to discover the S-SSB in the carrier.

Meanwhile, in the NR SL system, multiple numerologies having different SCS and/or CP lengths may be supported. In this case, as the SCS increases, the length of the time resource for a transmitting terminal to transmit an S-SSB may become shorter. Accordingly, the coverage of the S-SSB may decrease. Therefore, in order to ensure the coverage of the S-SSB, the transmitting terminal may transmit one or more S-SSBs to a receiving terminal within one S-SSB transmission period according to the SCS. For example, the number of S-SSBs that the transmitting terminal transmits to the receiving terminal within one S-SSB transmission period may be pre-configured or configured for the transmitting terminal. For example, the S-SSB transmission period may be 160 ms. For example, an S-SSB transmission period of 160 ms may be supported for all SCSs.

For example, when the SCS is 15 kHz at FR1, the transmitting terminal can transmit one or two S-SSBs to the receiving terminal within one S-SSB transmission period. For example, when the SCS is 30 kHz at FR1, the transmitting terminal can transmit one or two S-SSBs to the receiving terminal within one S-SSB transmission period. For example, when the SCS is 60 kHz at FR1, the transmitting terminal can transmit one, two, or four S-SSBs to the receiving terminal within one S-SSB transmission period.

FIG. 11 illustrates a procedure for a terminal to perform V2X or SL communication according to a transmission mode according to an embodiment of the present disclosure. The embodiment of FIG. 11 can be combined with various embodiments of the present disclosure. In various embodiments of the present disclosure, the transmission mode may be referred to as a mode or a resource allocation mode. Hereinafter, for convenience of explanation, the transmission mode in LTE may be referred to as an LTE transmission mode, and the transmission mode in NR may be referred to as an NR resource allocation mode.

For example, (a) of Fig. 11 represents a terminal operation related to LTE transmission mode 1 or LTE transmission mode 3. Or, for example, (a) of Fig. 11 represents a terminal operation related to NR resource allocation mode 1. For example, LTE transmission mode 1 can be applied to general SL communication, and LTE transmission mode 3 can be applied to V2X communication.

For example, (b) of Fig. 11 represents terminal operation related to LTE transmission mode 2 or LTE transmission mode 4. Or, for example, (b) of Fig. 11 represents terminal operation related to NR resource allocation mode 2.

Referring to (a) of FIG. 11, in LTE transmission mode 1, LTE transmission mode 3 or NR resource allocation mode 1, the base station may schedule SL resources to be used by the terminal for SL transmission. For example, in step S8000, the base station may transmit information related to SL resources and/or information related to UL resources to the first terminal. For example, the UL resources may include PUCCH resources and/or PUSCH resources. For example, the UL resources may be resources for reporting SL HARQ feedback to the base station.

For example, the first terminal may receive information related to a DG (dynamic grant) resource and/or information related to a CG (configured grant) resource from the base station. For example, the CG resource may include a CG type 1 resource or a CG type 2 resource. In this specification, the DG resource may be a resource that the base station configures/allocates to the first terminal via DCI (downlink control information). In this specification, the CG resource may be a (periodic) resource that the base station configures/allocates to the first terminal via DCI and/or an RRC message. For example, in case of a CG type 1 resource, the base station may transmit an RRC message including information related to the CG resource to the first terminal. For example, in case of a CG type 2 resource, the base station may transmit an RRC message including information related to the CG resource to the first terminal, and the base station may transmit DCI related to activation or release of the CG resource to the first terminal.

In step S8010, the first terminal may transmit a PSCCH (e.g., Sidelink Control Information (SCI) or 1st-stage SCI) to the second terminal based on the resource scheduling. In step S8020, the first terminal may transmit a PSSCH (e.g., 2nd-stage SCI, MAC PDU, data, etc.) related to the PSCCH to the second terminal. In step S8030, the first terminal may receive a PSFCH related to the PSCCH/PSSCH from the second terminal. For example, HARQ feedback information (e.g., NACK information or ACK information) may be received from the second terminal via the PSFCH. In step S8040, the first terminal may transmit/report HARQ feedback information to the base station via PUCCH or PUSCH. For example, the HARQ feedback information reported to the base station may be information that the first terminal generates based on the HARQ feedback information received from the second terminal. For example, the HARQ feedback information reported to the base station may be information that the first terminal generates based on a rule set in advance. For example, the DCI may be DCI for scheduling of SL. For example, the format of the DCI may be DCI format 3_0 or DCI format 3_1. Table 7 shows an example of DCI for scheduling of SL.

Referring to (b) of FIG. 11, in LTE transmission mode 2, LTE transmission mode 4 or NR resource allocation mode 2, a terminal may determine an SL transmission resource within an SL resource set by a base station/network or a preset SL resource. For example, the set SL resource or the preset SL resource may be a resource pool. For example, the terminal may autonomously select or schedule resources for SL transmission. For example, the terminal may perform SL communication by selecting a resource by itself within the set resource pool. For example, the terminal may perform sensing and resource (re)selection procedures to select a resource by itself within a selection window. For example, the sensing may be performed on a subchannel basis. For example, in step S8010, a first terminal that has selected a resource by itself within a resource pool may transmit a PSCCH (e.g., SCI (Sidelink Control Information) or 1st-stage SCI) to a second terminal using the resource. In step S8020, the first terminal can transmit a PSSCH (e.g., 2nd-stage SCI, MAC PDU, data, etc.) related to the PSCCH to the second terminal. In step S8030, the first terminal can receive a PSFCH related to the PSCCH/PSSCH from the second terminal.

Referring to (a) or (b) of FIG. 11, for example, the first terminal may transmit an SCI to the second terminal on the PSCCH. Or, for example, the first terminal may transmit two consecutive SCIs (e.g., 2-stage SCIs) to the second terminal on the PSCCH and/or the PSSCH. In this case, the second terminal may decode the two consecutive SCIs (e.g., 2-stage SCIs) to receive the PSSCH from the first terminal. In this specification, the SCI transmitted on the PSCCH may be referred to as a 1st SCI, a 1st SCI, a 1st-stage SCI, or a 1st-stage SCI format, and the SCI transmitted on the PSSCH may be referred to as a 2nd SCI, a 2nd SCI, a 2nd-stage SCI, or a 2nd-stage SCI format. For example, a 1st-stage SCI format may include SCI format 1-A, and a 2nd-stage SCI format may include SCI format 2-A and/or SCI format 2-B. Table 8 shows an example of a 1st-stage SCI format.

Table 9 shows an example of the 2nd-stage SCI format.

Referring to (a) or (b) of FIG. 11, in step S8030, the first terminal can receive PSFCH based on Table 10. For example, the first terminal and the second terminal can determine PSFCH resources based on Table 10, and the second terminal can transmit HARQ feedback to the first terminal using the PSFCH resources.

Referring to (a) of FIG. 11, in step S8040, the first terminal may transmit SL HARQ feedback to the base station through PUCCH and/or PUSCH based on Table 11.

Meanwhile, the following Table 12 is a disclosure related to selection and reselection of a sidelink relay UE in 3GPP TS 36.331. The disclosure of Table 12 is used as prior art of the present disclosure, and for necessary details related thereto, refer to 3GPP TS 36.331.

Figure 12 shows the connection management and the procedure for path switching from direct to indirect as captured in the TR document (3GPP TR 38.836) related to Rel-17 NR SL. The remote UE needs to establish its own PDU session/DRB with the network before transmitting user plane data.

The PC5-RRC aspect PC5 unicast link establishment procedure of Rel-16 NR V2X can be reused to establish a secure unicast link between the remote UE and the relay UE for L2 UE-to-Network relaying before the remote UE establishes a Uu RRC connection with the network via the relay UE.

For both in-coverage and out-of-coverage, when a remote UE initiates the first RRC message to establish connection with the gNB, the PC5 L2 configuration for transmission between the remote UE and the UE-to-Network Relay UE can be based on the RLC/MAC configuration defined in the standard. The establishment of Uu SRB1/SRB2 and DRB of the remote UE follows the legacy Uu configuration procedure for L2 UE-to-Network Relay.

The high-level connection setup procedure illustrated in Figure 12 applies to L2 UE-to-Network Relay.

At step S1200, the Remote and Relay UE can perform a discovery procedure and establish a PC5-RRC connection at step S1201 based on the existing Rel-16 procedure.

In step S1202, the remote UE can send the first RRC message (i.e., RRCSetupRequest) to establish connection with the gNB via the Relay UE using the default L2 configuration of PC5. The gNB responds (S1203) to the remote UE with an RRCSetup message. The RRCSetup delivery to the remote UE uses the default configuration of PC5. If the Relay UE is not started in RRC_CONNECTED, it needs to perform its own connection setup upon receiving the message for the default L2 configuration of PC5. Details for the Relay UE to deliver the RRCSetupRequest/RRCSetup message to the remote UE at this step can be discussed in the WI step.

In step S1204, the gNB and the Relay UE perform a relay channel setup procedure via Uu. Depending on the configuration of the gNB, the Relay/Remote UE sets up an RLC channel to relay SRB1 to the remote UE via PC5. This step prepares a relay channel for SRB1.

In step S1205, a remote UE SRB1 message (e.g., RRCSetupComplete message) is transmitted to the gNB through the relay UE using the SRB1 relay channel over PC5. And the remote UE is RRC connected over Uu.

In step S1206, the remote UE and the gNB establish security according to legacy procedures and the security message is delivered through the Relay UE.

In step S1210, the gNB sets up an additional RLC channel between the gNB and the Relay UE for traffic relay. Depending on the configuration of the gNB, the Relay/Remote UE sets up an additional RLC channel between the Remote UE and the Relay UE for traffic relay. The gNB sends RRCReconfiguration to the Remote UE through the Relay UE to set up the Relay SRB2/DRB. The Remote UE sends RRCReconfigurationComplete to the gNB through the Relay UE in response.

For L2 UE-to-Network relay, in addition to the connection setup procedure:

- RRC reconfiguration and RRC disconnection procedures can reuse legacy RRC procedures with message content/configuration design left in the WI phase.

- RRC connection re-establishment and RRC connection resumption procedures can reuse existing RRC procedures as a baseline by considering the connection establishment procedure of the above L2 UE-to-Network Relay to handle relay-specific parts along with message content/configuration design. Message content/configuration can be defined later.

Figure 13 illustrates a direct to indirect path transition. The procedure of Figure 13 can be used when a remote UE transitions to an indirect Relay UE for service continuity of L2 UE-to-Network Relay.

Referring to FIG. 13, in step S1301, the remote UE measures/discovers candidate relay UEs, and then reports one or more candidate relay UEs. The remote UE may filter appropriate relay UEs that meet higher layer criteria when reporting. The report may include ID and SL RSRP information of the relay UE, where details related to PC5 measurement may be determined later.

In step S1302, the gNB decides to switch to the target relay UE and the target (re)configuration is optionally transmitted to the relay UE.

In step S1304, the RRC reconfiguration message to the remote UE may include the ID of the target relay UE, the target Uu, and the PC5 configuration.

In step S1305, if the connection is not yet established, the remote UE establishes a PC5 connection with the target relay UE.

In step S1306, the remote UE feeds back RRCReconfigurationComplete to the gNB through the target path using the target configuration provided in RRCReconfiguration.

In step S1307, the data path is switched.

Tables 13 to 16 are 3GPP technical reports related to UE-to-UE Relay Selection and are used as prior art in the present disclosure. Fig. 14 in Table 14 and Fig. 15 in Table 16 correspond to Fig. 14 and Fig. 15, respectively.

6.8 Solution #8: UE-to-UE Relay Selection Without Relay Discovery 6.8.1 Description When a source UE wants to communicate with a target UE, it will first try to find the target UE by either sending a Direct Communication Request or a Solicitation message with the target UE info. If the source UE cannot reach the target UE directly, it will try to discover a UE-to-UE relay to reach the target UE which may also trigger the relay to discover the target UE. To be more efficient, this solution tries to integrate target UE discovery and UE-to-UE relay discovery and selection together, including two alternatives: - Alternative 1: UE-to-UE relay discovery and selection can be integrated into the unicast link establishment procedure as described in clause 6.3.3 of TS 23.287 [5]. - Alternative 2: UE-to-UE relay discovery and selection is integrated into Model B direct discovery procedure. A new field is proposed to be added in the Direct Communication Request or the Solicitation message to indicate whether relays can be used in the communication. The field can be called relay_indication. When a UE wants to broadcast a Direct Communication Request or a Solicitation message, it indicates in the message whether a UE-to-UE relay could be used. For Release 17, it is assumed that the value of the indication is restricted to single hop. When a UE-to-UE relay receives a Direct Communication Request or a Solicitation message with the relay_indication set, then it shall decide whether to forward the message (ie modify the message and broadcast it in its proximity), according to eg Relay Service Code if there is any, Application ID, authorization policy (eg relay for specific ProSe Service), the current traffic load of the relay, the radio conditions between the source UE and the relay UE, etc. It may exist a situation where multiple UE-to-UE relays can be used to reach the target UE or the target UE may also directly receive the Direct Communication Request or Solicitation message from the source UE. The target UE may choose which one to reply according to eg signal strength, local policy (eg traffic load of the UE-to-UE relays), Relay Service Code if there is any or operator policies (eg always prefer direct communication or only use some specific UE-to-UE relays). The source UE may receive the responses from multiple UE-to-UE relays and may also from the target UE directly, the source UE chooses the communication path according to eg signal strength or operator policies (eg always prefer direct communication or only use some specific UE-to-UE relays).

6.8.2 Procedures 6.8.2.1 UE-to-UE relay discovery and selection is integrated into the unicast link establishment procedure (Alternative 1) Fig 14 illustrates the procedure of the proposed method. 0. UEs are authorized to use the service provided by the UE-to-UE relays. UE-to-UE relays are authorized to provide service of relaying traffic among UEs. The authorization and the parameter provisioning can use solutions for KI#8, eg Sol#36. The authorization can be done when UEs/relays are registered to the network. Security related parameters may be provisioned so that a UE and a relay can verify the authorization with each other if needed. 1. UE-1 wants to establish unicast communication with UE-2 and the communication can be either through direct link with UE-2 or via a UE-to-UE relay. Then UE-1 broadcasts Direct Communication Request with relay_indication enabled. The message will be received by relay-1, relay-2. The message may also be received by UE-2 if it is in the proximity of UE-1. UE-1 includes source UE info, target UE info, Application ID, as well as Relay Service Code if there is any. If UE-1 does not want relay to be involved in the communication, then it will made relay_indication disabled. NOTE 1: The data type of relay_indication can be determined in Stage 3. Details of Direct Communication Request/Accept messages will be determined in stage 3. 2. Relay-1 and relay-2 decide to participate in the procedure. They broadcast a new Direct Communication Request message in their proximity without relay_indication enabled. If a relay receives this message, it will just drop it. When a relay broadcasts the Direct Communication Request message, it includes source UE info, target UE info and Relay UE info (eg Relay UE ID) in the message and use Relay's L2 address as the source Layer-2 ID. The Relay maintains association between the source UE information (eg source UE L2 ID) and the new Direct Communication Request. 3. UE-2 receives the Direct Communication Requests from relay-1 and relay-2. UE-2 may also receive Direct Communication Request message directly from the UE-1 if the UE-2 is in the communication range of UE-1. 4. UE-2 chooses relay-1 and replies with Direct Communication Accept message. If UE-2 directly receives the Direct Communication Request from UE-1, it may choose to setup a direct communication link by sending the Direct Communication Accept message directly to UE-1. After receiving Direct Communication Accept, a UE-to-UE relay retrieves the source UE information stored in step 2 and sends the Direct Communication Accept message to the source UE with its Relay UE info added in the message.

After step 4, UE-1 and UE-2 have respectively setup the PC5 links with the chosen UE-to-UE relay. NOTE 2: The security establishment between the UE1 and Relay-1, and between Relay-1 and UE-2 are performed before the Relay-1 and UE-2 send Direct Communication Accept message. Details of the authentication/security establishment procedure are determined by SA WG3. The security establishment procedure can be skipped if there already exists a PC5 link between the source (or target) UE and the relay which can be used for relaying the traffic. 5. UE-1 receives the Direct Communication Accept message from relay-1. UE-1 chooses path according to eg policies (eg always choose direct path if it is possible), signal strength, etc. If UE-1 receives Direct Communication Accept / Response message request accept directly from UE-2, it may choose to setup a direct PC5 L2 link with UE-2 as described in clause 6.3.3 of TS 23.287 [5], then step 6 is skipped. 6a. For the L3 UE-to-UE Relay case, UE-1 and UE-2 finish setting up the communication link via the chosen UE-to-UE relay. The link setup information may vary depending on the type of relay, eg L2 or L3 relaying. Then UE-1 and UE-2 can communicate via the relay. Regarding IP address allocation for the source/remote UE, the addresses can be either assigned by the relay or by the UE itself (eg link-local IP address) as defined in clause 6.3.3 of TS 23.287 [5]. 6b. For the Layer 2 UE-to-UE Relay case, the source and target UE can setup an end-to-end PC5 link via the relay. UE-1 sends a unicast E2E Direct Communication Request message to UE-2 via the Relay-1, and UE-2 responds with a unicast E2E Direct Communication Accept message to UE-1 via the Relay-1. Relay-1 transfers the messages based on the identity information of UE-1/UE-2 in the Adaptation Layer. NOTE 3: How Relay-1 can transfer the messages based on the identity information of UE-1/UE-2 in the Adaptation Layer requires cooperation with RAN2 during the normative phase. NOTE 4: In order to make a relay or path selection, the source UE can setup a timer after sending out the Direct Communication Request for collecting the corresponding response messages before making a decision. Similarly, the target UE can also setup a timer after receiving the first copy of the Direct Communication Request / message for collecting multiple copies of the message from different paths before making a decision. NOTE 5: In the first time when a UE receives a message from a UE-to-UE relay, the UE needs to verify if the relay is authorized to be a UE-to-UE relay. Similarly, the UE-to-UE relay may also need to verify if the UE is authorized to use the relay service. The verification details and the how to secure the communication between two UEs through a UE-to-UE relay is to be defined by SA WG3.

6.8.2.2 UE-to-UE relay discovery and selection is integrated into Model B direct discovery procedure (Alternative 2) Depicted in Fig 15 is the procedure for UE-UE Relay discovery Model B, and the discovery/selection procedure is separated from hop by hop and end-to-end link establishment. 1. UE-1 broadcasts discovery solicitation message carrying UE-1 info, target UE info (UE-2), Application ID, Relay Service Code if any, the UE-1 can also indicate relay_indication enabled. 2. On reception of discovery solicitation, the candidate Relay UE-R broadcasts discovery solicitation carrying UE-1 info, UE-R info, Target UE info. The Relay UE-R uses Relay's L2 address as the source Layer-2 ID. 3. The target UE-2 responds the discovery message. If the UE-2 receives discovery solicitation message in step 1, then UE-2 responds discovery response in step 3b with UE-1 info, UE-2 info. If not and UE-2 receives discovery solicitation in step 2, then UE-2 responds discovery response message in step 3a with UE-1 info, UE-R info, UE-2 info. 4. On reception of discovery response in step 3a, UE-R sends discovery response with UE-1 info, UE-R info, UE-2 info. If more than one candidate Relay UEs responding discovery response message, UE-1 can select one Relay UE based on eg implementation or link qualification. 5. The source and target UE may need to setup PC5 links with the relay before communicating with each other. Step 5a can be skipped if there already exists a PC5 link between the UE-1 and UE-R which can be used for relaying. Step 5b can be skipped if there already exists a PC5 link between the UE-2 and UE-R which can be used for relaying. 6a. Same as step 6a described in clause 6.8.2.1. 6b. For the Layer-2 UE-to-UE Relay, the E2E unicast Direct Communication Request message is sent from UE1 to the selected Relay via the per-hop link (established in steps 5a) and the Adaptation layer info identifying the peer UE (UE3 ) as the destination. The UE-to-UE Relay transfers the E2E messages based on the identity information of peer UE in the Adaptation Layer. The initiator (UE1) knows the Adaptation layer info identifying the peer UE (UE3) after a discovery procedure. UE3 responds with E2E unicast Direct Communication Accept message in the same way. NOTE 1: For the Layer 2 UE-to-UE Relay case, whether step5b is performed before step 6b or triggered during step 6b will be decided at normative phase. NOTE 2: How Relay-1 can transfer the messages based on the identity information of UE-1/UE-2 in the Adaptatin Layer requires cooperation with RAN2 during the normative phase. 6.8.3 Impacts on services, entities and interfaces UE impacts to support new Relay related functions.

The following Table 17 is a description related to Fig. 16 regarding the Architecture and Protocol Stack of the Layer-2 Relay. Fig. 16(a) illustrates a user plane protocol stack for an L2 UE-to-UE relay, and Fig. 16(b) illustrates a control plane protocol stack for an L2 UE-to-UE relay.

5.5 Layer-2 Relay 5.5.1 Architecture and Protocol Stack For L2 UE-to-UE Relay architecture, the protocol stacks are similar to L2 UE-to-Network Relay other than the fact that the termination points are two Remote UEs. The protocol stacks for the user plane and control plane of L2 UE-to-UE Relay architecture are described in Figure 5.5.1-1 and Figure 5.5.1-2. An adaptation layer is supported over the second PC5 link (ie the PC5 link between Relay UE and Destination UE) for L2 UE-to-UE Relay. For L2 UE-to-UE Relay, the adaptation layer is put over RLC sublayer for both CP and UP over the second PC5 link. The sidelink SDAP/PDCP and RRC are terminated between two Remote UEs, while RLC, MAC and PHY are terminated in each PC5 link. For the first hop of L2 UE-to-UE Relay, - The N:1 mapping is supported by first hop PC5 adaptation layer between Remote UE SL Radio Bearers and first hop PC5 RLC channels for relaying. - The adaptation layer over first PC5 hop between Source Remote UE and Relay UE supports to identify traffic destined to different Destination Remote UEs. For the second hop of L2 UE-to-UE Relay, - The second hop PC5 adaptation layer can be used to support bearer mapping between the ingress RLC channels over first PC5 hop and egress RLC channels over second PC5 hop at Relay UE. - PC5 Adaptation layer supports the N:1 bearer mapping between multiple ingress PC5 RLC channels over first PC5 hop and one egress PC5 RLC channel over second PC5 hop and supports the Remote UE identification function. For L2 UE-to-UE Relay, - The identity information of Remote UE end-to-end Radio Bearer is included in the adaptation layer in first and second PC5 hop. - In addition, the identity information of Source Remote UE and/or the identity information of Destination Remote UE are candidate information to be included in the adaptation layer, which are to be decided in WI phase.

16.1.2 LCP Restrictions With LCP restrictions in MAC, RRC can restrict the mapping of a logical channel to a subset of the configured cells, numerologies, PUSCH transmission durations, configured grant configurations and control whether a logical channel can utilize the resources allocated by a Type 1 Configured Grant (see clause 10.3) or whether a logical channel can utilize dynamic grants indicating a certain physical priority level. With such restrictions, it then becomes possible to reserve, for instance, the numerology with the largest subcarrier spacing and/or shortest PUSCH transmission duration for URLLC services. Furthermore, RRC can associate logical channels with different SR configurations, for instance, to provide more frequent SR opportunities to URLLC services. 16.1.3 Packet Duplication When duplication is configured for a radio bearer by RRC, at least one secondary RLC entity is added to the radio bearer to handle the duplicated PDCP PDUs as depicted on Figure 16.1.3-1, where the logical channel corresponding to the primary RLC entity is referred to as the primary logical channel, and the logical channel corresponding to the secondary RLC entity(ies), the secondary logical channel(s). All RLC entities have the same RLC mode. Duplication at PDCP therefore consists in submitting the same PDCP PDUs multiple times: once to each activated RLC entity for the radio bearer. With multiple independent transmission paths, packet duplication therefore increases reliability and reduces latency and is especially beneficial for URLLC services. NOTE: PDCP control PDUs are not duplicated and always submitted to the primary RLC entity. When configuring duplication for a DRB, RRC also sets the state of PDCP duplication (either activated or deactivated) at the time of (re-)configuration. After the configuration, the PDCP duplication state can then be dynamically controlled by means of a MAC control element and in DC, the UE applies the MAC CE commands regardless of their origin (MCG or SCG). When duplication is configured for an SRB the state is always active and cannot be dynamically controlled. When configuring duplication for a DRB with more than one secondary RLC entity, RRC also sets the state of each of them (ie either activated or deactivated). Subsequently, a MAC CE can be used to dynamically control whether each of the configured secondary RLC entities for a DRB should be activated or deactivated, ie which of the RLC entities shall be used for duplicate transmission. Primary RLC entity cannot be deactivated. When duplication is deactivated for a DRB, all secondary RLC entities associated to this DRB are deactivated. When a secondary RLC entity is deactivated, it is not re-established, the HARQ buffers are not flushed, and the transmitting PDCP entity should indicate to the secondary RLC entity to discard all duplicated PDCP PDUs. When activating duplication for a DRB, NG-RAN should ensure that at least one serving cell is activated for each logical channel associated with an activated RLC entity of the DRB; and when the deactivation of SCells leaves no serving cells activated for a logical channel of the DRB, NG-RAN should ensure that duplication is also deactivated for the RLC entity associated with the logical channel. When duplication is activated, the original PDCP PDU and the corresponding duplicate(s) shall not be transmitted on the same carrier. The logical channels of a radio bearer configured with duplication can either belong to the same MAC entity (referred to as CA duplication) or to different ones (referred to as DC duplication). CA duplication can also be configured in either or both of the MAC entities together with DC duplication when duplication over more than two RLC entities is configured for the radio bearer. In CA duplication, logical channel mapping restrictions are used in a MAC entity to ensure that the different logical channels of a radio bearer in the MAC entity are not sent on the same carrier. When CA duplication is configured for an SRB, one of the logical channels associated to the SRB is mapped to SpCell. When CA duplication is deactivated for a DRB in a MAC entity (ie none or only one of RLC entities of the DRB in the MAC entity remains activated), the logical channel mapping restrictions of the logical channels of the DRB are lifted for as long as CA duplication remains deactivated for the DRB in the MAC entity. When an RLC entity acknowledges the transmission of a PDCP PDU, the PDCP entity shall indicate to the other RLC entity(ies) to discard it. In addition, in case of CA duplication, when an RLC entity restricted to only SCell(s) reaches the maximum number of retransmissions for a PDCP PDU, the UE informs the gNB but does not trigger RLF.

Meanwhile, a UE-to-UE relay (U2U relay) may also require operations similar to those of the current multi-path U2N relay. Similar to the operation of the current multi-path U2N relay UE, a remote UE performing UE-to-UE relay operation may also have a direct link and an indirect link in order to increase the reliability of the U2U relay operation. Therefore, the following disclosure of the present invention proposes matters that can be considered when multi-path U2U is applied to the UE-to-UE relay operation.

In the following description, the source remote UE may be called a U2U remote UE, the target remote UE may be called a peer U2U remote UE, and the relay UE may be called a U2U relay UE.

In one embodiment, a source remote UE can establish a direct link with a target remote UE. In addition, the source remote UE can establish an end-to-end link, corresponding to an indirect link, with the target remote UE via a relay UE. Thereafter, the source remote UE can activate at least one of the direct link and the indirect link. The source remote UE can transmit a message to the target remote UE via the activated link.

The upper layer of the source remote UE can inform the AS layer of a first ID set including a first SRC ID and a first DST ID used for the indirect link, together with a second ID set including a second SRC ID and a second DST ID related to the direct link. Accordingly, the source remote UE can consider the indirect link corresponding to the first ID set and the direct link corresponding to the second ID set as links connecting to the same target remote UE.

In more detail, as illustrated in FIG. 18, when a source remote UE and a target remote UE have both a direct link and an indirect link, the upper layer of the source remote UE can set the SRC/DST UE ID to be used for the indirect link (wherein the DST ID is the SRC ID of the Relay/target remote UE) and the SRC/DST L2 ID to be used for the direct link to different values and inform the AS layer of this. However, the source remote UE may need to know that the direct link and the indirect link are links connecting to the same target remote UE. Therefore, when the upper layer informs the AS layer of the SRC L2 ID or the DST L2 ID (of the direct/indirect link), it can indicate that the corresponding L2 IDs are associated with each other.

At least one of the activations of the above direct link and indirect link may be performed based on RSRP (Reference Signals Received Power). Split bearer may also be applied to multi-path UE-to-UE operation. As illustrated in FIG. 20, a packet may be duplicated in the PDCP layer and transmitted through the direct path and the indirect path. In this case, the activation/deactivation of the RLC entity in the SL is determined by the source remote UE (and/or the target remote UE). This is different from the activation/deactivation of the RLC entity in the CA/DC (Carrier aggregation/Dual Connectivity) operation, which follows the configuration of the gNB. In addition, in the existing CA/DC operation, there are primary RLC entities and secondary RLC entities, and the primary RLC entity is not deactivated. However, in the multi-path UE-to-UE relay operation, this primary RLC entity concept may not be necessary. Therefore, both may be dynamically activated/deactivated. That is, the above direct link and indirect link may be allowed to be activated simultaneously regardless of the primary RLC entity.

The method may further include that the source remote UE selects the relay UE associated with the addition of the indirect link, and the source remote UE establishes an SL connection with the relay UE. The source remote UE may consider that multi-path is established based on receiving a response to RRCReconfigurationSidelink transmitted through the indirect link through the direct link. In summary, as illustrated in FIG. 21, addition of an indirect path in a state where a direct path exists may be performed by the following procedure. The source remote UE selects a relay UE for UE2UE relay operation. The source remote UE and the selected relay UE establish an SL connection (1st-hop), and the relay UE and the target remote UE also establish an SL connection (2nd-hop). Thereafter, the source remote UE and the target remote UE may establish an SL connection for setting up an end-to-end bearer through the relay UE through the indirect link. Since this is a process in which multi-path is established, the response to the RRCReconfigurationSidelink message transmitted from the source remote UE to the target remote UE via the relay UE may be made via the direct link. That is, if the source remote UE receives a response (RRCReconfigurationCompleteSidelink) message to the RRCReconfigurationSidelink transmitted via the indirect link via the direct link, the source remote UE may consider that multi-path is established.

Alternatively, as illustrated in FIG. 22, when adding a direct link while there is an indirect link, the source remote UE may set up RRCReconfiguration through the direct link, and in response, the RRCReconfigurationComplete message may be sent through the previously set up indirect link.

Meanwhile, with respect to the PDCP duplication described above, the upper layer of the source remote UE can indicate whether PDCP duplication is performed on a per-bearer (and/or per-PQI) basis. If PDCP duplication is indicated on a per-PQI basis, duplication can be processed as activated for a bearer that includes at least one PQI for which PQI duplication is activated. This is because multiple PQIs can be multiplexed and transmitted on a single bearer.

When PDCP duplication is allowed, the method for the source remote UE to dynamically determine activation/deactivation of the RLC entity at the AS layer can be as follows:

First, based on the RSRP threshold of the bearer related to the direct path and the bearer related to the indirect path being equal to or greater than a reference value, the source remote UE can arbitrarily deactivate either an RLC entity existing in the direct path or an RLC entity existing in the indirect path. In other words, if the RSRP threshold of the direct path (the bearer existing in) and the indirect path (the bearer existing in) are equal to or greater than a reference value, the source remote UE can arbitrarily deactivate either an RLC entity existing in the direct path or an RLC entity existing in the indirect path. Or, if a primary RLC entity is determined, the secondary RLC entity is deactivated. Or, whether to deactivate a certain RLC entity may be determined by a higher layer of the source remote UE. The RSRP threshold value may be determined by a higher layer of the source remote UE, and the threshold for the indirect path and the threshold for the direct path may be different. That is, the RSRP threshold value can be a value set by the upper layer of the source remote UE, and can be a value that takes QoS into account. In addition, the threshold for the indirect path and the threshold for the direct path can be different. When determining the RSRP value of the indirect path, it can be selected as a value that considers not only the RSRP between the source remote UE and the relay UE, but also the RSRP between the relay UE and the target remote UE. In addition, this threshold value can be a value that is set differently depending on the SL bearer that the source remote UE wants to transmit.

Second, based on the RSRP thresholds of the bearer related to the direct path and the bearer related to the indirect path being less than or equal to a reference value, the source remote UE can transmit a message through both an RLC entity existing in the direct path and an RLC entity existing in the indirect path. That is, when the RSRP thresholds of the direct path (the bearer existing in) and the indirect path (the bearer existing in) are less than or equal to a reference value, the source remote UE can transmit a message through both an RLC entity existing in the direct path and an RLC entity existing in the indirect path. That is, both direct/indirect RLC entities are activated.

Thirdly, based on whether the signal strength of the direct path or the signal strength of the indirect path is lower than or equal to the RSRP threshold, the source remote UE can transmit a message through a path whose signal strength is higher than or equal to the RSRP threshold. That is, if the signal strength of either the direct path or the indirect path is lower than or equal to the threshold (the threshold value may be applied differently depending on the bearer), the source remote UE transmits data through a path whose signal strength is higher than or equal to the threshold.

Meanwhile, in UE-to-UE operation, when the upper layer of the source remote UE sends the source L2 ID (SRC_A) and the target L2 ID (DST_A) to the AS layer, it can notify another source ID (SRC_B) and target L2 ID (DST_B) associated therewith. At this time, the {SRC_A, DST_A} set can be a value used for communication between the source remote UE and the relay UE, and the {SRC_B, DST_B} set can be a value used for communication between the source remote UE and the target remote UE. Accordingly, when the source remote UE transmits a message to the relay UE, the SRAP header includes any value (and/or both values) of the {SRC_B, DST_B} set, and at this time, the value used in the AS layer (e.g., MAC/PHY layer) can be the {SRC_A, DST_A} set value. At this time, SRC_A and SRC_B can be the same value. If the values of SRC_A and SRC_B are the same, the upper layer of the remote UE can forward only one DST_B (L2 ID of the target remote UE) associated with {SRC_A, DST_A} set to the AS layer.

Whether the source remote UE and the target remote UE will set up and use split bearer may require mutual negotiation. For example, a source remote UE that wants to set up split bearer may include split bearer-related configuration when transmitting an RRCReconfigurationSidelink message through the direct/indirect path. In this case, if the target remote UE transmits an RRCReconfigurationCompleteSidelink message in response, the split bearer is considered to have been set up and can be operated.

A source remote UE can configure a measurement report to a target remote UE. If the source remote UE and the target remote UE have an indirect link, measurement for the (not yet established) direct link can be configured. That is, the target remote UE can be configured to measure the direct link with the source remote UE. In this case, the value measured by the target remote UE can be a message that the source remote UE transmits to the relay UE. Therefore, when the source remote UE configures the measurement to the target remote UE, it can inform the L2 ID of the source remote UE and the L2 ID of the relay UE. This is because the target remote UE may not know the L2 ID of the source remote UE and the L2 ID of the relay UE that it needs to measure. In this case, the target remote UE that has received the measurement configuration can overhear a message between the source remote UE and the relay UE (signal strength for data transmitted from the source remote UE and received by the relay UE) and measure the signal strength.

When PDCP duplication is allowed, the target remote UE may transmit a MAC CE to the source remote UE, recommending activation/deactivation of the RLC entity, in a way that the source remote UE dynamically determines activation/deactivation of the RLC entity at the AS layer. The MAC CE can be transmitted over both (or either) the direct and indirect paths.

When an RLF occurs, the RLF can be reported through another available path. When an RLF occurs on the direct path, the remote UE can report an RLF (cause value: direct path RLF) through the indirect link. Or, when an RLF occurs on the indirect path, for example, when the remote UE detects an RLF between the relay UE and the remote UE, it can report it through the direct path (cause value: indirect path RLF). Or, when the remote UE receives a notification from the relay UE that an RLF occurs between the relay UE and a peer remote UE, it can report it through the direct path (cause value: indirect path RLF from receiving notification).

In connection with the above description, a source remote UE comprises at least one processor; and at least one computer memory operably connected to the at least one processor and storing instructions that, when executed, cause the at least one processor to perform operations, the operations comprising: establishing a direct link with a target remote UE; establishing an end-to-end link with the target remote UE, via a relay UE, corresponding to an indirect link; activating at least one of the direct link and the indirect link; and transmitting a message to the target remote UE via the activated link, wherein an upper layer of the source remote UE can notify an AS layer of a first ID set including a first SRC ID, a first DST ID used for the indirect link, together with a second ID set including a second SRC ID, a second DST ID associated with the direct link.

Also, a non-volatile computer-readable storage medium storing at least one computer program comprising instructions that, when executed by at least one processor, cause the at least one processor to perform operations for a source remote UE, the operations comprising: establishing a direct link with a target remote UE; establishing an end-to-end link with the target remote UE, via a relay UE, corresponding to an indirect link; activating at least one of the direct link and the indirect link; and transmitting a message to the target remote UE via the activated link, wherein an upper layer of the source remote UE can notify an AS layer of a first ID set including a first SRC ID and a first DST ID used for the indirect link together with a second ID set including a second SRC ID and a second DST ID associated with the direct link.

According to the above embodiment, multi-path operation is possible in U2U operation. In addition, efficient path activation/deactivation is possible when PDCP duplication is allowed. Therefore, by increasing data reliability and transmitting packets using only one path when channel conditions are good, transmission resources can be used dynamically and efficiently.

In the above description, it is obvious that the relay UE can be extended to gNB, IAB-node, etc. In the above description, the source remote UE can be cross-interpreted as the target remote UE, and the target remote UE can be cross-interpreted as the source remote UE. (For example, both can correspond to end-remote-UE)

Examples of communication systems to which the present disclosure applies

Although not limited thereto, the various descriptions, functions, procedures, proposals, methods, and/or operational flowcharts of the present disclosure disclosed in this document may be applied to various fields requiring wireless communication/connectivity (e.g., 5G) between devices.

Hereinafter, more specific examples will be provided with reference to the drawings. In the drawings/descriptions below, the same drawing reference numerals may represent identical or corresponding hardware blocks, software blocks, or functional blocks, unless otherwise described.

Fig. 23 illustrates a communication system (1) applied to the present disclosure.

Referring to FIG. 23, a communication system (1) applied to the present disclosure includes a wireless device, a base station, and a network. Here, the wireless device means a device that performs communication using a wireless access technology (e.g., 5G NR (New RAT), LTE (Long Term Evolution)) and may be referred to as a communication/wireless/5G device. Although not limited thereto, the wireless device may include a robot (100a), a vehicle (100b-1, 100b-2), an XR (eXtended Reality) device (100c), a hand-held device (100d), a home appliance (100e), an IoT (Internet of Thing) device (100f), and an AI device/server (400). For example, the vehicle may include a vehicle equipped with a wireless communication function, an autonomous vehicle, a vehicle capable of performing vehicle-to-vehicle communication, etc. Here, the vehicle may include an Unmanned Aerial Vehicle (UAV) (e.g., a drone). XR devices include AR (Augmented Reality)/VR (Virtual Reality)/MR (Mixed Reality) devices and can be implemented in the form of HMD (Head-Mounted Device), HUD (Head-Up Display) installed in a vehicle, television, smartphone, computer, wearable device, home appliance, digital signage, vehicle, robot, etc. Portable devices can include smartphone, smart pad, wearable device (e.g., smart watch, smart glass), computer (e.g., laptop, etc.). Home appliances can include TV, refrigerator, washing machine, etc. IoT devices can include sensors, smart meters, etc. For example, base stations and networks can also be implemented as wireless devices, and a specific wireless device (200a) can act as a base station/network node to other wireless devices.

Wireless devices (100a to 100f) can be connected to a network (300) via a base station (200). Artificial Intelligence (AI) technology can be applied to the wireless devices (100a to 100f), and the wireless devices (100a to 100f) can be connected to an AI server (400) via the network (300). The network (300) can be configured using a 3G network, a 4G (e.g., LTE) network, a 5G (e.g., NR) network, etc. The wireless devices (100a to 100f) can communicate with each other via the base station (200)/network (300), but can also communicate directly (e.g., sidelink communication) without going through the base station/network. For example, vehicles (100b-1, 100b-2) can communicate directly (e.g. V2V (Vehicle to Vehicle)/V2X (Vehicle to everything) communication). Also, IoT devices (e.g., sensors) can communicate directly with other IoT devices (e.g., sensors) or other wireless devices (100a to 100f).

Wireless communication/connection (150a, 150b, 150c) can be established between wireless devices (100a to 100f)/base stations (200), and base stations (200)/base stations (200). Here, the wireless communication/connection can be achieved through various wireless access technologies (e.g., 5G NR) such as uplink/downlink communication (150a), sidelink communication (150b) (or, D2D communication), and communication between base stations (150c) (e.g., relay, IAB (Integrated Access Backhaul)). Through the wireless communication/connection (150a, 150b, 150c), a wireless device and a base station/wireless device, and a base station and a base station can transmit/receive wireless signals to/from each other. For example, the wireless communication/connection (150a, 150b, 150c) can transmit/receive signals through various physical channels. To this end, at least some of various configuration information setting processes for transmitting/receiving wireless signals, various signal processing processes (e.g., channel encoding/decoding, modulation/demodulation, resource mapping/demapping, etc.), and resource allocation processes can be performed based on various proposals of the present disclosure.

Examples of wireless devices to which this disclosure applies

FIG. 24 illustrates a wireless device applicable to the present disclosure.

Referring to FIG. 24, the first wireless device (100) and the second wireless device (200) can transmit and receive wireless signals through various wireless access technologies (e.g., LTE, NR). Here, {the first wireless device (100), the second wireless device (200)} can correspond to {the wireless device (100x), the base station (200)} and/or {the wireless device (100x), the wireless device (100x)} of FIG. 23.

A first wireless device (100) includes one or more processors (102) and one or more memories (104), and may additionally include one or more transceivers (106) and/or one or more antennas (108). The processor (102) controls the memories (104) and/or the transceivers (106), and may be configured to implement the descriptions, functions, procedures, suggestions, methods, and/or operational flowcharts disclosed in this document. For example, the processor (102) may process information in the memory (104) to generate first information/signal, and then transmit a wireless signal including the first information/signal via the transceiver (106). Additionally, the processor (102) may receive a wireless signal including second information/signal via the transceiver (106), and then store information obtained from signal processing of the second information/signal in the memory (104). The memory (104) may be connected to the processor (102) and may store various information related to the operation of the processor (102). For example, the memory (104) may perform some or all of the processes controlled by the processor (102), or may store software codes including instructions for performing the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document. Here, the processor (102) and the memory (104) may be part of a communication modem/circuit/chip designed to implement wireless communication technology (e.g., LTE, NR). The transceiver (106) may be connected to the processor (102) and may transmit and/or receive wireless signals via one or more antennas (108). The transceiver (106) may include a transmitter and/or a receiver. The transceiver (106) may be used interchangeably with an RF (Radio Frequency) unit. In the present disclosure, a wireless device may also mean a communication modem/circuit/chip.

The second wireless device (200) includes one or more processors (202), one or more memories (204), and may additionally include one or more transceivers (206) and/or one or more antennas (208). The processor (202) may be configured to control the memories (204) and/or the transceivers (206), and implement the descriptions, functions, procedures, suggestions, methods, and/or operational flowcharts disclosed in this document. For example, the processor (202) may process information in the memory (204) to generate third information/signals, and then transmit a wireless signal including the third information/signals via the transceivers (206). Additionally, the processor (202) may receive a wireless signal including fourth information/signals via the transceivers (206), and then store information obtained from signal processing of the fourth information/signals in the memory (204). The memory (204) may be connected to the processor (202) and may store various information related to the operation of the processor (202). For example, the memory (204) may perform some or all of the processes controlled by the processor (202), or may store software codes including instructions for performing the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in the present document. Here, the processor (202) and the memory (204) may be part of a communication modem/circuit/chip designed to implement wireless communication technology (e.g., LTE, NR). The transceiver (206) may be connected to the processor (202) and may transmit and/or receive wireless signals via one or more antennas (208). The transceiver (206) may include a transmitter and/or a receiver. The transceiver (206) may be used interchangeably with an RF unit. In the present disclosure, a wireless device may also mean a communication modem/circuit/chip.

Hereinafter, hardware elements of the wireless device (100, 200) will be described in more detail. Although not limited thereto, one or more protocol layers may be implemented by one or more processors (102, 202). For example, one or more processors (102, 202) may implement one or more layers (e.g., functional layers such as PHY, MAC, RLC, PDCP, RRC, SDAP). One or more processors (102, 202) may generate one or more Protocol Data Units (PDUs) and/or one or more Service Data Units (SDUs) according to the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document. One or more processors (102, 202) may generate messages, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed in this document. One or more processors (102, 202) can generate signals (e.g., baseband signals) comprising PDUs, SDUs, messages, control information, data or information according to the functions, procedures, suggestions and/or methodologies disclosed herein, and provide the signals to one or more transceivers (106, 206). One or more processors (102, 202) can receive signals (e.g., baseband signals) from one or more transceivers (106, 206) and obtain PDUs, SDUs, messages, control information, data or information according to the descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed herein.

The one or more processors (102, 202) may be referred to as a controller, a microcontroller, a microprocessor, or a microcomputer. The one or more processors (102, 202) may be implemented by hardware, firmware, software, or a combination thereof. For example, one or more Application Specific Integrated Circuits (ASICs), one or more Digital Signal Processors (DSPs), one or more Digital Signal Processing Devices (DSPDs), one or more Programmable Logic Devices (PLDs), or one or more Field Programmable Gate Arrays (FPGAs) may be included in the one or more processors (102, 202). The descriptions, functions, procedures, suggestions, methods, and/or operational flowcharts disclosed in this document may be implemented using firmware or software, and the firmware or software may be implemented to include modules, procedures, functions, etc. The descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in this document may be implemented using firmware or software configured to perform one or more of the following: included in one or more processors (102, 202), or stored in one or more memories (104, 204) and driven by one or more of the processors (102, 202). The descriptions, functions, procedures, suggestions, methods and/or operational flowcharts disclosed in this document may be implemented using firmware or software in the form of codes, instructions and/or sets of instructions.

One or more memories (104, 204) may be coupled to one or more processors (102, 202) and may store various forms of data, signals, messages, information, programs, codes, instructions and/or commands. The one or more memories (104, 204) may be comprised of ROM, RAM, EPROM, flash memory, hard drives, registers, cache memory, computer readable storage media and/or combinations thereof. The one or more memories (104, 204) may be located internally and/or externally to the one or more processors (102, 202). Additionally, the one or more memories (104, 204) may be coupled to the one or more processors (102, 202) via various technologies, such as wired or wireless connections.

One or more transceivers (106, 206) can transmit user data, control information, wireless signals/channels, etc., as described in the methods and/or flowcharts of this document, to one or more other devices. One or more transceivers (106, 206) can receive user data, control information, wireless signals/channels, etc., as described in the descriptions, functions, procedures, suggestions, methods and/or flowcharts of this document, from one or more other devices. For example, one or more transceivers (106, 206) can be coupled to one or more processors (102, 202) and can transmit and receive wireless signals. For example, one or more processors (102, 202) can control one or more transceivers (106, 206) to transmit user data, control information, or wireless signals to one or more other devices. Additionally, one or more processors (102, 202) may control one or more transceivers (106, 206) to receive user data, control information, or wireless signals from one or more other devices. Additionally, one or more transceivers (106, 206) may be coupled to one or more antennas (108, 208), and one or more transceivers (106, 206) may be configured to transmit and receive user data, control information, wireless signals/channels, and the like, as referred to in the descriptions, functions, procedures, proposals, methods, and/or operational flowcharts disclosed herein, via one or more antennas (108, 208). In this document, one or more antennas may be multiple physical antennas, or multiple logical antennas (e.g., antenna ports). One or more transceivers (106, 206) may convert received user data, control information, wireless signals/channels, etc. from RF band signals to baseband signals in order to process the received user data, control information, wireless signals/channels, etc. using one or more processors (102, 202). One or more transceivers (106, 206) may convert processed user data, control information, wireless signals/channels, etc. from baseband signals to RF band signals using one or more processors (102, 202). For this purpose, one or more transceivers (106, 206) may include an (analog) oscillator and/or filter.

Examples of vehicles or autonomous vehicles to which this disclosure applies

Fig. 25 illustrates a vehicle or autonomous vehicle to which the present disclosure applies. The vehicle or autonomous vehicle may be implemented as a mobile robot, a car, a train, a manned/unmanned aerial vehicle (AV), a ship, etc.

Referring to FIG. 25, a vehicle or autonomous vehicle (100) may include an antenna unit (108), a communication unit (110), a control unit (120), a driving unit (140a), a power supply unit (140b), a sensor unit (140c), and an autonomous driving unit (140d). The antenna unit (108) may be configured as a part of the communication unit (110).

The communication unit (110) can transmit and receive signals (e.g., data, control signals, etc.) with external devices such as other vehicles, base stations (e.g., base stations, road side units, etc.), servers, etc. The control unit (120) can control elements of the vehicle or autonomous vehicle (100) to perform various operations. The control unit (120) can include an ECU (Electronic Control Unit). The drive unit (140a) can drive the vehicle or autonomous vehicle (100) on the ground. The drive unit (140a) can include an engine, a motor, a power train, wheels, brakes, a steering device, etc. The power supply unit (140b) supplies power to the vehicle or autonomous vehicle (100) and can include a wired/wireless charging circuit, a battery, etc. The sensor unit (140c) can obtain vehicle status, surrounding environment information, user information, etc. The sensor unit (140c) may include an IMU (inertial measurement unit) sensor, a collision sensor, a wheel sensor, a speed sensor, an incline sensor, a weight detection sensor, a heading sensor, a position module, a vehicle forward/backward sensor, a battery sensor, a fuel sensor, a tire sensor, a steering sensor, a temperature sensor, a humidity sensor, an ultrasonic sensor, a light sensor, a pedal position sensor, etc. The autonomous driving unit (140d) may implement a technology for maintaining a driving lane, a technology for automatically controlling speed such as adaptive cruise control, a technology for automatically driving along a set path, a technology for automatically setting a path and driving when a destination is set, etc.

For example, the communication unit (110) can receive map data, traffic information data, etc. from an external server. The autonomous driving unit (140d) can generate an autonomous driving route and a driving plan based on the acquired data. The control unit (120) can control the driving unit (140a) so that the vehicle or autonomous vehicle (100) moves along the autonomous driving route according to the driving plan (e.g., speed/direction control). During autonomous driving, the communication unit (110) can irregularly/periodically acquire the latest traffic information data from an external server and can acquire surrounding traffic information data from surrounding vehicles. In addition, the sensor unit (140c) can acquire vehicle status and surrounding environment information during autonomous driving. The autonomous driving unit (140d) can update the autonomous driving route and driving plan based on the newly acquired data/information. The communication unit (110) can transmit information on the vehicle location, autonomous driving route, driving plan, etc. to an external server. External servers can predict traffic information data in advance using AI technology, etc. based on information collected from vehicles or autonomous vehicles, and provide the predicted traffic information data to vehicles or autonomous vehicles.

Examples of AR/VR and vehicles to which this disclosure applies

Fig. 26 illustrates a vehicle to which the present disclosure applies. The vehicle may also be implemented as a means of transportation, a train, an aircraft, a ship, etc.

Referring to FIG. 26, the vehicle (100) may include a communication unit (110), a control unit (120), a memory unit (130), an input/output unit (140a), and a position measurement unit (140b).

The communication unit (110) can transmit and receive signals (e.g., data, control signals, etc.) with other vehicles or external devices such as base stations. The control unit (120) can control components of the vehicle (100) to perform various operations. The memory unit (130) can store data/parameters/programs/codes/commands that support various functions of the vehicle (100). The input/output unit (140a) can output AR/VR objects based on information in the memory unit (130). The input/output unit (140a) can include a HUD. The position measurement unit (140b) can obtain position information of the vehicle (100). The position information can include absolute position information of the vehicle (100), position information within a driving line, acceleration information, position information with respect to surrounding vehicles, etc. The position measurement unit (140b) can include GPS and various sensors.

For example, the communication unit (110) of the vehicle (100) can receive map information, traffic information, etc. from an external server and store them in the memory unit (130). The location measurement unit (140b) can obtain vehicle location information through GPS and various sensors and store them in the memory unit (130). The control unit (120) can generate a virtual object based on the map information, traffic information, vehicle location information, etc., and the input/output unit (140a) can display the generated virtual object on the vehicle window (1410, 1420). In addition, the control unit (120) can determine whether the vehicle (100) is being driven normally within the driving line based on the vehicle location information. If the vehicle (100) abnormally deviates from the driving line, the control unit (120) can display a warning on the vehicle window through the input/output unit (140a). In addition, the control unit (120) can broadcast a warning message regarding driving abnormalities to surrounding vehicles through the communication unit (110). Depending on the situation, the control unit (120) can transmit vehicle location information and information regarding driving/vehicle abnormalities to relevant organizations through the communication unit (110).

Examples of XR devices to which this disclosure applies

Fig. 27 illustrates an XR device applicable to the present disclosure. The XR device may be implemented as an HMD, a HUD (Head-Up Display) equipped in a vehicle, a television, a smartphone, a computer, a wearable device, a home appliance, a digital signage, a vehicle, a robot, etc.

Referring to FIG. 27, the XR device (100a) may include a communication unit (110), a control unit (120), a memory unit (130), an input/output unit (140a), a sensor unit (140b), and a power supply unit (140c).

The communication unit (110) can transmit and receive signals (e.g., media data, control signals, etc.) with external devices such as other wireless devices, portable devices, or media servers. The media data can include videos, images, sounds, etc. The control unit (120) can control components of the XR device (100a) to perform various operations. For example, the control unit (120) can be configured to control and/or perform procedures such as video/image acquisition, (video/image) encoding, metadata generation and processing, etc. The memory unit (130) can store data/parameters/programs/codes/commands required for driving the XR device (100a)/generation of XR objects. The input/output unit (140a) can obtain control information, data, etc. from the outside, and output the generated XR object. The input/output unit (140a) can include a camera, a microphone, a user input unit, a display unit, a speaker, and/or a haptic module. The sensor unit (140b) can obtain the XR device status, surrounding environment information, user information, etc. The sensor unit (140b) can include a proximity sensor, a light sensor, an acceleration sensor, a magnetic sensor, a gyro sensor, an inertial sensor, an RGB sensor, an IR sensor, a fingerprint recognition sensor, an ultrasonic sensor, a light sensor, a microphone, and/or a radar, etc. The power supply unit (140c) supplies power to the XR device (100a) and can include a wired/wireless charging circuit, a battery, etc.

For example, the memory unit (130) of the XR device (100a) may include information (e.g., data, etc.) required for creating an XR object (e.g., AR/VR/MR object). The input/output unit (140a) may obtain a command to operate the XR device (100a) from a user, and the control unit (120) may operate the XR device (100a) according to the user's operating command. For example, when a user attempts to watch a movie, news, etc. through the XR device (100a), the control unit (120) may transmit content request information to another device (e.g., a mobile device (100b)) or a media server through the communication unit (130). The communication unit (130) may download/stream content such as a movie or news from another device (e.g., a mobile device (100b)) or a media server to the memory unit (130). The control unit (120) controls and/or performs procedures such as video/image acquisition, (video/image) encoding, and metadata generation/processing for content, and can generate/output an XR object based on information about surrounding space or real objects acquired through the input/output unit (140a)/sensor unit (140b).

In addition, the XR device (100a) is wirelessly connected to the mobile device (100b) through the communication unit (110), and the operation of the XR device (100a) can be controlled by the mobile device (100b). For example, the mobile device (100b) can act as a controller for the XR device (100a). To this end, the XR device (100a) can obtain three-dimensional position information of the mobile device (100b), and then generate and output an XR object corresponding to the mobile device (100b).

Robot examples to which this disclosure applies

Fig. 28 illustrates a robot applicable to the present disclosure. Robots can be classified into industrial, medical, household, military, etc., depending on the purpose or field of use.

Referring to FIG. 28, the robot (100) may include a communication unit (110), a control unit (120), a memory unit (130), an input/output unit (140a), a sensor unit (140b), and a driving unit (140c).

The communication unit (110) can transmit and receive signals (e.g., driving information, control signals, etc.) with external devices such as other wireless devices, other robots, or control servers. The control unit (120) can control components of the robot (100) to perform various operations. The memory unit (130) can store data/parameters/programs/codes/commands that support various functions of the robot (100). The input/output unit (140a) can obtain information from the outside of the robot (100) and output information to the outside of the robot (100). The input/output unit (140a) can include a camera, a microphone, a user input unit, a display unit, a speaker, and/or a haptic module. The sensor unit (140b) can obtain internal information of the robot (100), surrounding environment information, user information, etc. The sensor unit (140b) may include a proximity sensor, an illuminance sensor, an acceleration sensor, a magnetic sensor, a gyro sensor, an inertial sensor, an IR sensor, a fingerprint recognition sensor, an ultrasonic sensor, a light sensor, a microphone, a radar, etc. The driving unit (140c) may perform various physical operations, such as moving a robot joint. In addition, the driving unit (140c) may allow the robot (100) to drive on the ground or fly in the air. The driving unit (140c) may include an actuator, a motor, wheels, brakes, a propeller, etc.

Examples of AI devices to which this disclosure applies

Fig. 29 illustrates an AI device applicable to the present disclosure. The AI device may be implemented as a fixed device or a movable device, such as a TV, a projector, a smartphone, a PC, a laptop, a digital broadcasting terminal, a tablet PC, a wearable device, a set-top box (STB), a radio, a washing machine, a refrigerator, a digital signage, a robot, a vehicle, etc.

Referring to FIG. 29, the AI device (100) may include a communication unit (110), a control unit (120), a memory unit (130), an input/output unit (140a/140b), a learning processor unit (140c), and a sensor unit (140d).

The communication unit (110) can transmit and receive wired and wireless signals (e.g., sensor information, user input, learning models, control signals, etc.) with external devices such as other AI devices (e.g., 100x, 200, 400 of FIG. 23) or AI servers (e.g., 400 of FIG. 23) using wired and wireless communication technology. To this end, the communication unit (110) can transmit information in the memory unit (130) to the external device or transfer a signal received from the external device to the memory unit (130).

The control unit (120) may determine at least one executable operation of the AI device (100) based on information determined or generated using a data analysis algorithm or a machine learning algorithm. Then, the control unit (120) may control components of the AI device (100) to perform the determined operation. For example, the control unit (120) may request, search, receive, or utilize data of the learning processor unit (140c) or the memory unit (130), and control components of the AI device (100) to perform a predicted operation or an operation determined to be desirable among at least one executable operation. In addition, the control unit (120) may collect history information including operation contents of the AI device (100) or user feedback on the operation, and store the information in the memory unit (130) or the learning processor unit (140c), or transmit the information to an external device such as an AI server (FIG. 23, 400). The collected history information may be used to update a learning model.

The memory unit (130) can store data that supports various functions of the AI device (100). For example, the memory unit (130) can store data obtained from the input unit (140a), data obtained from the communication unit (110), output data of the learning processor unit (140c), and data obtained from the sensing unit (140). In addition, the memory unit (130) can store control information and/or software codes necessary for the operation/execution of the control unit (120).

The input unit (140a) can obtain various types of data from the outside of the AI device (100). For example, the input unit (140a) can obtain learning data for model learning, and input data to which the learning model is to be applied. The input unit (140a) may include a camera, a microphone, and/or a user input unit. The output unit (140b) may generate output related to vision, hearing, or touch. The output unit (140b) may include a display unit, a speaker, and/or a haptic module. The sensing unit (140) may obtain at least one of internal information of the AI device (100), surrounding environment information of the AI device (100), and user information using various sensors. The sensing unit (140) may include a proximity sensor, an illuminance sensor, an acceleration sensor, a magnetic sensor, a gyro sensor, an inertial sensor, an RGB sensor, an IR sensor, a fingerprint recognition sensor, an ultrasonic sensor, a light sensor, a microphone, and/or a radar.

The learning processor unit (140c) can train a model composed of an artificial neural network using learning data. The learning processor unit (140c) can perform AI processing together with the learning processor unit of the AI server (Fig. 23, 400). The learning processor unit (140c) can process information received from an external device through the communication unit (110) and/or information stored in the memory unit (130). In addition, the output value of the learning processor unit (140c) can be transmitted to an external device through the communication unit (110) and/or stored in the memory unit (130).

The embodiments described above can be applied to various mobile communication systems.

Claims (13)

1. In a method for operating a source remote UE (User Equipment) in a UE-to-UE relay in a wireless communication system,

   The above source remote UE establishes a direct link with the target remote UE;

   The above source remote UE establishes an end-to-end link with the target remote UE, corresponding to an indirect link, via the relay UE;

   The above source remote UE activates at least one of the direct link and the indirect link;

   The above source remote UE transmits a message to the target remote UE through the above activated link;

   Including,

   A method in which the upper layer of the source remote UE notifies the AS layer of a first ID set including a first SRC ID and a first DST ID used for the indirect link, together with a second ID set including a second SRC ID and a second DST ID related to the direct link.
2. In the first paragraph,

   A method in which the source remote UE considers the indirect link corresponding to the first ID set and the direct link corresponding to the second ID set as links connected to the same target remote UE.
3. In the first paragraph,

   A method wherein at least one of the direct link and the indirect link is activated based on RSRP (Reference Signals Received Power).
4. In the first paragraph,

   A method in which the above direct link and indirect link allow simultaneous activation regardless of the primary RLC entity.
5. In the first paragraph,

   The above method,

   The above source remote UE selects the relay UE associated with the addition of the indirect link;

   The above source remote UE establishes an SL connection with the above relay UE;

   A method further comprising:
6. In paragraph 5,

   A method in which the source remote UE considers that multi-path is established based on receiving a response to RRCReconfigurationSidelink transmitted through the indirect link through the direct link.
7. In the first paragraph,

   A method in which the source remote UE randomly deactivates one of an RLC entity existing in the direct path and an RLC entity existing in the indirect path based on the RSRP threshold of the bearer related to the direct path and the bearer related to the indirect path being equal to or greater than a reference value.
8. In Article 7,

   A method wherein the above RSRP threshold value is determined by a higher layer of the source remote UE.
9. In Article 8,

   A method wherein the threshold for the indirect path and the threshold for the direct path are different.
10. In Article 7,

    A method in which the source remote UE transmits a message through both an RLC entity existing in the direct path and an RLC entity existing in the indirect path, based on the RSRP threshold of a bearer related to the direct path and a bearer related to the indirect path being less than or equal to a reference value.
11. In the first paragraph,

    A method wherein, based on whether either the signal strength of the direct path or the signal strength of the indirect path is lower than or equal to the RSRP threshold, the source remote UE transmits a message through a path whose signal strength is higher than or equal to the RSRP threshold.
12. In a wireless communication system, in a UE-to-UE relay, at a source remote UE,

    at least one processor; and

    At least one computer memory operably connected to said at least one processor and storing instructions that, when executed, cause said at least one processor to perform operations;

    The above actions are,

    Establish a direct link with the target remote UE;

    Establishing an end-to-end link with the target remote UE, corresponding to the indirect link, via the relay UE;

    Activate at least one of the above direct links and indirect links;

    Transmit a message to the target remote UE through the activated link;

    Including,

    The upper layer of the source remote UE notifies the AS layer of a first ID set including a first SRC ID and a first DST ID used for the indirect link, together with a second ID set including a second SRC ID and a second DST ID related to the direct link.
13. A nonvolatile computer-readable storage medium storing at least one computer program comprising instructions that, when executed by at least one processor, cause the at least one processor to perform operations for a source remote UE,

    The above actions are,

    Establish a direct link with the target remote UE;

    Establishing an end-to-end link with the target remote UE, corresponding to the indirect link, via the relay UE;

    Activate at least one of the above direct links and indirect links;

    Transmit a message to the target remote UE through the activated link;

    Including,

    A storage medium in which the upper layer of the source remote UE notifies the AS layer of a first ID set including a first SRC ID and a first DST ID used for the indirect link together with a second ID set including a second SRC ID and a second DST ID related to the direct link.

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