Method of operating a source base station related to handover of a remote UE in a wireless communication system

Abstract

One embodiment according to the present invention is a method for operating a source base station related to handover (HO) of a remote user equipment (UE) in a wireless communication system, the method comprising: receiving measurement results from the remote UE by the source base station; selecting a target base station for HO of the remote UE by the source base station; and transmitting a HO request message to the target base station by the source base station, wherein the HO request message includes information indicating one or more candidate relay UEs, and the one or more candidate relay UEs belong to the target base station.

Description

Technical Field

[0001] The following description relates to a wireless communication system, and more particularly, to an operation method and apparatus of a source base station related to the determination of an indirect path when a remote UE performs a handover, etc.

Background Art

[0002] In a wireless communication system, various RATs (Radio Access Technologies) such as LTE, LTE-A, and WiFi are used, and 5G is also included here. Three areas of the main requirements of 5G include (1) an enhanced mobile broadband (eMBB) area, (2) a massive machine type communication (mMTC) area, and (3) an ultra-reliable and low latency communications (URLLC) area. In some use cases, multiple areas are required for optimization, and in other use cases, it is also possible to focus only on one core performance indicator (KPI). 5G is to support such various use cases in a flexible and reliable manner.

[0003] eMBB goes beyond basic mobile Internet access to cover rich two-way operations, media and entertainment applications in the cloud or extended reality. Data is one of the core drivers of 5G, and for the first time in the 5G era, dedicated voice services may not be seen. In 5G, voice is expected to be processed 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 transmission rates. Streaming services (audio and video), conversational video, and mobile Internet connections are more widely used as more devices are connected to the Internet. Such numerous applications require always-on connectivity to push real-time information and notifications to users. Cloud storage and applications are increasing rapidly on mobile communication platforms, which can be applied to both business and entertainment. Also, cloud storage is a special use case that drives the growth of uplink data transmission rates. 5G is also used for cloud remote operations and requires a very low end-to-end latency to maintain an excellent user experience when a tactile interface is used. Entertainment, such as cloud gaming and video streaming, is another core element that increases the requirements for mobile broadband capabilities. Entertainment is essential on smartphones and tablets everywhere, including high-mobility environments such as cars, vehicles, and airplanes. Further use cases include extended reality and information search for entertainment. Here, extended reality requires very low latency and instantaneous data volume.

[0004] Another widely anticipated use case for 5G is the ability to smoothly connect embedded sensors across all fields, namely, mMTC. It is predicted that the number of potential IoT devices will reach 20.4 billion by 2020. Industrial IoT is one of the areas where 5G plays a major role in enabling smart cities, asset tracking, smart utility, agriculture, and security infrastructure.

[0005] URLLC includes new services that transform industries through remote control of critical infrastructure and ultra-reliable / low-latency links such as self-driving vehicles. The levels of reliability and latency are essential for smart grid control, industrial automation, robotics, drone control, and regulation.

[0006] Next, more specific descriptions will be given for a number of use cases.

[0007] 5G is a means of providing streams that are evaluated from hundreds of megabytes per second to gigabytes per second, and can complement fiber-to-the-home (FTTH) and cable-based broadband (or DOCSIS). Such high speeds are required not only for virtual reality and augmented reality, but also for transmitting TV at resolutions above 4K (6K, 8K, and higher). VR (Virtual Reality) and AR (Augmented Reality) applications include nearly immersive sports competitions. Special network settings may be required for specific applications. For example, in the case of VR games, integration between the core server and the edge network server of the network operator is necessary for game makers to minimize latency.

[0008] Automobiles, along with numerous use cases for mobile communication to vehicles, are expected to be a significant new driver in 5G. For example, entertainment for passengers requires high simultaneous capacity and high-mobility mobile broadband. This is because future users expect high-quality connectivity regardless of their location and speed. Another use case in the automotive field is the augmented reality dashboard. This overlays and displays information on the front windshield the driver is looking through, identifying objects in the dark and informing the driver of the distance and movement of the objects. Future wireless modules will enable communication between vehicles, information exchange between vehicles and supporting infrastructure, and information exchange between automobiles and other connected devices (e.g., devices accompanied by pedestrians). Safety systems can guide alternative courses of action to reduce the risk of accidents for safer driving by the driver. The next step is remote control or self-driven vehicles. This requires very high reliability and very fast communication between different self-driven vehicles and between automobiles and infrastructure. In the future, self-driven vehicles will perform all driving activities, and drivers will only focus on traffic anomalies that the vehicle itself cannot identify. The technical requirements for self-driven vehicles demand ultra-low latency and ultra-high-speed reliability to increase traffic safety to levels that humans cannot achieve.

[0009] Smart cities and smart homes, referred to as the smart society, are embedded in high-density wireless sensor networks. A distributed network of intelligent sensors identifies conditions related to the cost and energy-efficient maintenance of the city or home. Similar settings are made for each household. Temperature sensors, window and heating controls, burglary alarms, and household appliances are all wirelessly connected. Most of these sensors typically have low data transmission speeds, low power consumption, and low cost. However, for example, real-time HD video is required by certain types of devices for surveillance.

[0010] The consumption and distribution of energy, including heat or gas, are highly decentralized, and automated control of distributed sensor networks is required. Smart grids collect information and interconnect such sensors using digital information and communication technologies to operate thereby. Since this information includes the behavior of suppliers and consumers, smart grids can improve the distribution of fuels such as electricity in terms of efficiency, reliability, economy, production sustainability, and automation. Smart grids also appear to be other sensor networks with low latency.

[0011] The health segment has many applications that benefit from mobile communications. The communication system supports telemedicine, which provides clinical care from a distance. This can overcome the barrier of distance and improve access to medical services that are not continuously available in remote rural areas. It is also used to save lives in critical medical and emergency situations. Wireless sensor networks of mobile communication infrastructure can provide remote monitoring and sensors for parameters such as heart rate and blood pressure.

[0012] Wireless and mobile communications are becoming increasingly important in industrial applications. Wiring is expensive to install and maintain. Therefore, the possibility of alternation to wireless links that reconfigure cables is an attractive opportunity in many industrial fields. However, achieving this requires that wireless connections operate with the same latency, reliability, and capacity as cables, and that their management is simplified. Low latency and very low error rates are new requirements that need to be connected to 5G.

[0013] Logistics and freight tracking are important use cases for mobile communications that enable inventory and package tracking anywhere using location-based information systems. Use cases for logistics and freight tracking typically require low data speeds but wide coverage and reliable location information.

[0014] A wireless communication system is a multiple access system that shares available system resources (such as bandwidth, transmission power, etc.) to support communication with multiple users. Examples of multiple access systems include CDMA (code division multiple access) systems, FDMA (frequency division multiple access) systems, TDMA (time division multiple access) systems, OFDMA (orthogonal frequency division multiple access) systems, SC-FDMA (single carrier frequency division multiple access) systems, MC-FDMA (multi carrier frequency division multiple access) systems, and the like.

[0015] Sidelink (SL) refers to a communication method in which a direct link is established between terminals (User Equipment, UE), and voice or data, etc. is directly exchanged between the terminals without going through a base station (Base Station, BS). SL is one solution to solve the burden on the base station due to the rapidly increasing data traffic.

[0016] V2X (vehicle-to-everything) means a communication technology that exchanges information with other vehicles, pedestrians, infrastructure-built things, etc. through wired or wireless communication. V2X is classified into four types such as V2V (vehicle-to-vehicle), V2I (vehicle-to-infrastructure), V2N (vehicle-to-network), and V2P (vehicle-to-pedestrian). V2X communication is provided by the PC5 interface and / or the Uu interface.

[0017] On the one hand, as more communication devices demand greater communication capacity, there is an emerging need for mobile broadband communication that is improved compared to existing radio access technologies (RATs). As a result, communication systems that take into account services or terminals sensitive to reliability and latency are being discussed. Next-generation radio access technologies that consider enhanced mobile broadband communication, massive MTC, URLLC (Ultra-Reliable and Low Latency Communication), etc. are called new radio access technology (new RAT) or NR (new radio). V2X (vehicle-to-everything) communication can also be supported in NR.

[0018] FIG. 1 is a diagram for explaining a comparison between V2X communication based on RAT prior to NR and V2X communication based on NR.

[0019] Regarding V2X communication, in RAT prior to NR, solutions 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 discussed. V2X messages include location information, dynamic information, attribute information, etc. For example, a terminal can send a CAM of the periodic message type and / or a DENM of the event triggered message type to other terminals.

[0020] For example, CAM includes basic vehicle information such as dynamic state information of the vehicle, such as direction and speed, static vehicle data such as dimensions, external lighting conditions, route details, etc. For example, the terminal can broadcast CAM, and the delay of CAM is less than 100 ms. For example, when an emergency situation such as a vehicle failure or accident occurs, the terminal can generate a DENM and send it to other terminals. For example, all vehicles within the transmission range of the terminal can receive CAM and / or DENM. In this case, DENM has a higher priority than CAM.

[0021] Subsequently, various V2X scenarios are defined in NR in relation to V2X communication. For example, various V2X scenarios include vehicle platooning, enhanced driving, extended sensors, remote driving, etc.

[0022] For example, based on vehicle platooning, vehicles dynamically form a group and move together. For example, in order to perform platoon operations based on vehicle platooning, the vehicles belonging to the above group receive periodic data from the leading vehicle. For example, the vehicles belonging to the above group can use the periodic data to reduce or increase the vehicle - to - vehicle interval.

[0023] For example, based on enhanced driving, the vehicle is semi - automated or fully automated. Each vehicle can adjust its trajectories or maneuvers based on data obtained from local sensors of neighboring vehicles and / or neighboring logical entities. For example, each vehicle can share its driving intention with neighboring vehicles.

[0024] For example, based on extended sensors, raw data, processed data, or live video data obtained by local sensors can be exchanged between vehicles, logic elements, pedestrian terminals, and / or V2X application servers. Therefore, for example, a vehicle can recognize an environment that is better than the environment that can be sensed using its own sensors.

[0025] 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 a V2X application can operate or control the remote vehicle. For example, when the route can be predicted, such as in public transportation, cloud computing-based driving is used for the operation or control of the remote vehicle. For example, a connection to a cloud-based back-end service platform is considered for remote driving.

[0026] On the other hand, solutions for specifying service requirements for various V2X scenarios such as platooning vehicles, enhanced driving, extended sensors, and remote driving are being discussed in NR-based V2X communication.

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0027] The present disclosure has a technical problem related to an operation method and apparatus of a source base station related to determination of an indirect path and the like when a remote UE performs a handover.

MEANS FOR SOLVING THE PROBLEMS

[0028] One embodiment is a method for operating a source base station related to handover (HO) of a remote user equipment (User Equipment (UE)) in a wireless communication system, the method including: the source base station receiving measurement results from the remote UE; the source base station selecting a target base station for HO of the remote UE; and the source base station transmitting a HO request message to the target base station, wherein the HO request message includes information indicating one or more candidate relay UEs, and the one or more candidate relay UEs belong to the target base station.

[0029] One embodiment is a method for operating a target base station related to handover (HO) of a remote user equipment (User Equipment (UE)) in a wireless communication system, the method including: the target base station receiving a HO request message including information indicating one or more candidate relay UEs from a source base station; the target base station selecting a relay UE from among the one or more candidate relay UEs; and the target base station transmitting an RRCReconfiguration message to the remote UE, wherein the one or more candidate relay UEs belong to the target base station.

[0030] One embodiment is a target base station in a wireless communication system, including at least one processor and at least one computer memory operably coupled to the at least one processor and storing instructions that, when executed, cause the at least one processor to perform operations, the operations including: the target base station receiving a HO request message including information indicating one or more candidate relay UEs from a source base station; the target base station selecting a relay UE from among the one or more candidate relay UEs; and the target base station transmitting an RRCReconfiguration message to the remote UE, wherein the one or more candidate relay UEs belong to the target base station.

[0031] After the source base station decides to perform a handover (HO) of the remote UE to the target base station, it determines whether to use an indirect path or a direct path.

[0032] The information indicating the one or more candidate relay UEs is included in the HO request message based on the source base station's determination to use an indirect path after deciding to perform an HO of the remote UE to the target base station.

[0033] The information indicating the one or more candidate relay UEs is transmitted based on the source base station's determination to use an indirect path after the remote UE has been handed over to the target base station.

[0034] The information indicating the one or more candidate relay UEs includes one or more of the sidelink reference signal received power (SL-RSRP) for each candidate relay UE, the sidelink discovery RSRP (SD-RSRP), the L2 ID of the candidate relay UE, and the L2 ID of the remote UE.

[0035] The HO request message includes one or more of the sidelink reference signal received power (SL-RSRP) for each candidate relay UE, the sidelink discovery RSRP (SD-RSRP), the L2 ID of the candidate relay UE, and the L2 ID of the remote UE.

[0036] The serving base station transmits one or more of the sidelink reference signal received power (SL-RSRP) for each candidate relay UE, the sidelink discovery RSRP (SD-RSRP), the L2 ID of the candidate relay UE, and the L2 ID of the remote UE to the target base station via the Xn interface.

[0037] The source base station transmits the RRCReconfiguration message sent by the target base station to the remote UE.

[0038] The HO request message is one of the XnAP Handover Req and NGAP Handover Required messages.

Advantages of the Invention

[0039] According to one embodiment, in consideration of the fact that the source base station knows the measurement results between uu and the candidate relay UE, after deciding to HO the remote UE to the target base station, it is possible to most efficiently determine whether to use the indirect path or the direct path.

Brief Description of the Drawings

[0040] The drawings attached to this specification are for assisting in understanding the embodiments, showing various embodiments, and explaining the principles together with the description in the specification.

[0041]

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Modes for Carrying Out the Invention

[0042] In various embodiments of the present invention, " / " and "," indicate "and / or". For example, "A / B" means "A and / or B". Also, "A, B" also means "A and / or B". "A / B / C" means "any one of A, B and / or C". Also, "A, B, C" also means "any one of A, B and / or C".

[0043] In various embodiments of the present invention, "or" indicates "and / or". For example, "A or B" includes "only A", "only B", and / or "both A and B". In other words, "or" can be interpreted as "further or alternatively".

[0044] The following technologies can be used in various wireless connection systems such as CDMA (Code Division Multiple Access), FDMA (Frequency Division Multiple Access), TDMA (Time Division Multiple Access), OFDMA (Orthogonal Frequency Division Multiple Access), SC-FDMA (Single Carrier Frequency Division Multiple Access), etc. CDMA can be implemented by radio technologies such as UTRA (Universal Terrestrial Radio Access) and CDMA2000. TDMA can be implemented by radio 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 by radio technologies such as IEEE802.11 (Wi-Fi), IEEE802.16 (WiMAX), IEEE802-20, E-UTRA (Evolved UTRA), etc. IEEE 802.16m is an evolution of IEEE 802.16e and provides backward compatibility with systems based on IEEE 802.16e. UTRA is part of UMTS (Universal Mobile Telecommunications System). 3GPP (registered trademark) LTE (long term evolution) is part of E-UMTS (Evolved UMTS) that uses E-UTRA, adopts OFDMA in the downlink, and adopts SC-FDMA in the uplink. LTE-A (Advanced) is an evolution of 3GPP LTE.

[0045] 5G NR is a technology that follows LTE-A and is a new clean-slate mobile communication system with characteristics such as high performance, low latency, and high availability. 5G NR can utilize all available spectrum resources, including low-frequency bands below 1 GHz, intermediate-frequency bands from 1 GHz to 10 GHz, and high-frequency (millimeter-wave) bands above 24 GHz.

[0046] For a clearer explanation, the description will be centered around LTE-A or 5G NR, but the technical idea according to an embodiment of the present invention is not limited to these.

[0047] FIG. 2 shows the structure of an LTE system according to an embodiment of the present invention. This is also referred to as E-UTRAN (Evolved-UMTS Terrestrial Radio Access Network), or an LTE (Long Term Evolution) / LTE-A system.

[0048] Referring to FIG. 2, E-UTRAN includes a base station 20 that provides a control plane and a user plane to the terminal 10. The terminal 10 can be fixed or mobile and is also referred to by terms such as MS (mobile station), UT (user terminal), SS (Subscriber station), MT (mobile terminal), and wireless device. Generally, the base station 20 is a fixed station that communicates with the terminal 10 and is also referred to by applications such as eNB (evolved NodE-B), BTS (base transceiver system), and AP (access point).

[0049] The base stations 20 are connected to each other through the X2 interface. The base station 20 is connected to the EPC (evolved Packet core, 30) through the S1 interface, more specifically, to the MME (mobility management entity) through S1-MME and to the S-GW (Serving gateway) via S1-U.

[0050] The EPC30 is composed of an MME, an S-GW, and a P-GW (Packet data network-gateway). The MME has connection information of the terminal and information regarding the capabilities of the terminal, and such information is mainly used for the mobility management of the terminal. The S-GW is a gateway with the E-UTRAN as an end point, and the P-GW is a gateway with the PDN (Packet Date Network) as an end point.

[0051] The radio interface protocol layer between the terminal and the network is classified into a first layer (L1), a second layer (L2), and a third layer (L3) based on the lower three layers of the well-known Open System Interconnection (OSI) reference model in a communication system. Among them, the physical layer belonging to the first layer provides an information transmission service using physical channels, and the RRC (Radio Resource Control) layer belonging to the third layer controls radio resources between the terminal and the network. For this purpose, the RRC layer exchanges RRC messages between the terminal and the base station.

[0052] FIG. 3(a) shows a radio protocol architecture for a user plane according to an embodiment of the present invention.

[0053] FIG. 3(b) shows a radio protocol architecture for a control plane according to an embodiment of the present invention. The user plane is a protocol stack for user data transmission, and the control plane is a protocol stack for control signal transmission.

[0054] Referring to FIG. 3(a) and A3, the physical layer provides an information transmission service to the upper layer using a physical channel. The physical layer is connected to the upper layer, the MAC (Medium Access Control) layer, via a transport channel. Data moves between the MAC layer and the physical layer via the transport channel. The transport channel is classified according to how the data is transmitted and what characteristics it has through a wireless interface.

[0055] Between different physical layers, that is, between the physical layers of the transmitter and the receiver, data moves via a physical channel. The physical channel is modulated by the OFDM (Orthogonal Frequency Division Multiplexing) method and utilizes time and frequency as radio resources.

[0056] The MAC layer provides a service to the upper layer, the RLC (radio link control) layer, via a logical channel. The MAC layer provides a mapping function from multiple logical channels to multiple transport channels. Also, the MAC layer provides a logical channel multiplexing function by mapping multiple logical channels to a single transport channel. The MAC layer provides a data transmission service on the logical channel.

[0057] The RLC layer performs concatenation, segmentation, and reassembly of RLC SDUs (Serving Data Units). To ensure various QoS (Quality of Service) requirements of the Radio Bearer (RB), the RLC layer provides three operating modes: Transparent Mode (TM), Unacknowledged Mode (UM), and Acknowledged Mode (AM). AM RLC provides error correction by ARQ (automatic repeat request).

[0058] 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. An RB means 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.

[0059] The functions of the PDCP layer in the user plane include the transmission of user data, header compression, and ciphering. The functions of the PDCP layer in the control plane include the transmission and ciphering / integrity protection of control plane data.

[0060] When an RB is configured, it means the process of defining the characteristics of radio protocol layers and channels to provide a specific service and setting each specific parameter and operation method. An RB is further divided into two types: SRB (Signaling Radio Bearer) and DRB (Data Radio Bearer). The SRB is used as a path for transmitting RRC messages in the control plane, and the DRB is used as a path for transmitting user data in the user plane.

[0061] When an RRC connection is established between the RRC layer of the terminal and the RRC layer of the E-UTRAN, the terminal enters the RRC_CONNECTED state; otherwise, it enters the RRC_IDLE state. In the case of NR, an RRC_INACTIVE state is further defined. A terminal in the RRC_INACTIVE state can maintain the connection with the core network while releasing the connection with the base station.

[0062] As a downlink transmission channel for transmitting data to a terminal in a network, there are a BCH (Broadcast Channel) for transmitting system information and a downlink SCH (Shared Channel) for transmitting user traffic and control messages other than that. In the case of downlink multicast or block service traffic or control messages, they are transmitted via the downlink SCH or via another downlink MCH (Multicast Channel). On the other hand, as an uplink transmission channel for transmitting data from a terminal to a network, there are a RACH (Random Access Channel) for transmitting an initial control message and an uplink SCH (Shared Channel) for transmitting user traffic and control messages other than that.

[0063] Above the transmission channel, logical channels (Logical Channel) mapped to the transmission channel include BCCH (Broadcast Control Channel), PCCH (Paging Control Channel), CCCH (Common Control Channel), MCCH (Multicast Control Channel), MTCH (Multicast Traffic Channel), etc.

[0064] The physical channel (Physical Channel) is composed of a plurality of OFDM symbols in the time domain and a plurality of subcarriers in the frequency domain. One subframe is composed of a plurality of OFDM symbols in the time domain. A resource block is a resource allocation unit and is composed of a plurality of OFDM symbols and a plurality of subcarriers. Also, each subframe can use a specific subcarrier of a specific OFDM symbol (for example, the first OFDM symbol) of the corresponding subframe for the PDCCH (Physical Downlink Control Channel), that is, the L1 / L2 control channel. The TTI (Transmission Time Interval) is the unit time of subframe transmission.

[0065] Figure 4 shows the structure of an NR system according to an embodiment of the present invention.

[0066] Referring to Figure 4, the NG-RAN (Next Generation - Radio Access Network) includes a gNB (next generation - Node BF cell) and / or an eNB that provides user plane and control plane protocol termination to the terminal. The case including only the gNB is illustrated in Figure 4. The gNB and the eNB are connected to each other by an Xn interface. The gNB and the eNB are connected to the fifth generation core network (5G Core Network: 5GC) by an NG interface. More specifically, it is connected to the AMF (access and mobility management function) by an NG-C interface and to the UPF (user plane function) by an NG-U interface.

[0067] Figure 5 shows the functional split between the NG-RAN and the 5GC according to an embodiment of the present invention.

[0068] Referring to FIG. 5, the gNB provides functions such as Inter Cell RRM, Radio Bearer control, Connection Mobility Control, Radio Admission Control, Measurement configuration & Provision, and dynamic resource allocation. The AMF provides functions such as NAS security and idle state mobility handling. The UPF provides functions such as Mobility Anchoring and PDU (Protocol Data Unit) processing. The SMF (Session Management Function) provides functions such as terminal IP (Internet Protocol) address allocation and PDU session control.

[0069] FIG. 6 shows the structure of an NR radio frame to which an embodiment of the present invention is applicable.

[0070] Referring to FIG. 6, in NR, radio frames are used for uplink and downlink transmissions. The radio frame has a length of 10 ms and is defined by two 5-ms half-frames (HF). The half-frame includes five 1-ms subframes (SF). The subframe is divided into one or more slots, and the number of slots in the subframe depends on the subcarrier spacing (SCS). Each slot includes 12 or 14 OFDM(A) symbols by means of a CP (cyclic prefix).

[0071] When normal CP is used, each slot includes 14 symbols. When extended CP is used, each slot includes 12 symbols. Here, the symbol includes an OFDM symbol (or CP-OFDM symbol) and an SC-FDMA symbol (or DFT-s-OFDM symbol).

[0072] Table 1 illustrates the number of symbols per slot (N slot symbol ), the number of slots per frame (N frame,u slot ), and the number of slots per subframe (N subframe,u slot ) for different SCS settings (μ) when general CP is used.

[0073]

Table 1

[0074] Table 2 illustrates the number of symbols per slot, the number of slots per frame, and the number of slots per subframe for different SCS when extended CP is used.

[0075]

Table 2

[0076] In the NR system, the OFDM(A) numerology (e.g., SCS, CP length, etc.) can be set differently among multiple cells merged into one terminal. As a result, the (absolute time) intervals of time resources (e.g., subframes, slots, or TTIs) (collectively referred to as TUs (Time Unit) for convenience) composed of the same number of symbols are set differently among the merged cells.

[0077] In NR, a number of new numerologies or SCSs are supported to assist various 5G services. For example, when the SCS is 15 kHz, a wide area in traditional cellular bands is supported, and when the SCS is 30 kHz / 60 kHz, dense-urban, lower latency, and wider carrier bandwidth are supported. When the SCS is 60 kHz or higher, a bandwidth greater than 24.25 GHz is supported to overcome phase noise.

[0078] The NR frequency band is defined by two types of frequency ranges. The two types of frequency ranges are FR1 and FR2. The numerical values of the frequency ranges are changeable. For example, the two types of frequency ranges are as shown in Table 3 below. Among the frequency ranges used in the NR system, FR1 means "sub 6GHz range", and FR2 means "above 6GHz range", which is also called millimeter wave (mmW).

[0079]

Table 3

[0080] As described above, the numerical values of the frequency ranges in the NR system are changeable. For example, FR1 includes a band from 410 MHz to 7125 MHz as shown in Table 4 below. That is, FR1 includes frequency bands above 6 GHz (or 5850, 5900, 5925 MHz, etc.). For example, the frequency bands above 6 GHz (or 5850, 5900, 5925 MHz, etc.) included within FR1 include unlicensed bands. Unlicensed bands are used for various purposes, for example, for communication for vehicles (e.g., autonomous driving).

[0081]

Table 4

[0082] FIG. 7 is a diagram showing the slot structure of an NR frame according to an embodiment of the present invention.

[0083] Referring to FIG. 7, a slot includes a plurality of symbols in the time domain. For example, in the case of normal CP, one slot includes 14 symbols, while in the case of extended CP, one slot includes 12 symbols. Or, in the case of normal CP, one slot includes 7 symbols, while in the case of extended CP, one slot includes 6 symbols.

[0084] A carrier wave includes a plurality of sub-carrier waves in the frequency domain. An RB (Resource Block) is defined as a plurality (e.g., 12) of consecutive sub-carrier waves in the frequency domain. A BWP is defined as a plurality of consecutive PRBs (Physical RBs) in the frequency domain and corresponds to one numerology (e.g., SCS, CP length, etc.). A carrier wave includes a maximum of N (e.g., 5) BWPs. Data communication is performed on the activated BWP. Each element is referred to as a resource element (RE) in the resource grid, and one complex symbol can be mapped thereto.

[0085] On the other hand, a wireless interface between terminals or a wireless interface between a terminal and a network is composed of an L1 layer, an L2 layer, and an L3 layer. In various embodiments of the present invention, the L1 layer means a physical layer. The L2 layer means, for example, any one of a MAC layer, an RLC layer, a PDCP layer, and an SDAP layer. The L3 layer means, for example, an RRC layer.

[0086] Hereinafter, V2X or SL (sidelink) communication will be described.

[0087] Figure 8 shows the radio protocol architecture for SL communication according to an embodiment of the present invention. More specifically, FIG. 8(a) shows the user plane protocol stack of LTE, and FIG. 8(b) shows the control plane protocol stack of LTE.

[0088] Figure 9 shows the radio protocol architecture for SL communication according to an embodiment of the present invention. More specifically, FIG. 9(a) shows the user plane protocol stack of NR, and FIG. 9(b) shows the control plane protocol stack of NR.

[0089] Figure 10 shows the synchronization source or synchronization reference for V2X according to an embodiment of the present invention.

[0090] Referring to Figure 10, in V2X, a terminal is directly synchronized to GNSS (Global Navigation Satellite Systems), or indirectly synchronized to GNSS by a terminal that is directly synchronized to GNSS (inside or outside the network coverage). When GNSS is set as the synchronization source, the terminal uses UTC (Coordinated Universal Time) and a (pre-set) DFN (Direct Frame Number) offset to calculate the DFN and subframe number.

[0091] Alternatively, the terminal is synchronized directly to the base station or to another terminal whose time / frequency is synchronized to the base station. For example, the base station is an eNB or a gNB. For example, if the terminal is within the network coverage, the terminal receives the synchronization information provided by the base station and is synchronized directly to the base station. Then, the terminal provides the synchronization information to other adjacent terminals. When the base station timing is set as the synchronization reference, the terminal follows the cell related to the frequency (if within the cell coverage at the frequency), the primary cell or the serving cell (if outside the cell coverage at the frequency) for synchronization and downlink measurement.

[0092] The base station (e.g., the serving cell) provides synchronization settings for the carrier used for V2X or SL communication. In this case, the terminal follows the synchronization settings received from the base station. If the terminal does not detect any cell in the carrier used for V2X or SL communication and does not receive synchronization settings from the serving cell, the terminal follows the pre-set synchronization settings.

[0093] Alternatively, the terminal may be synchronized to another terminal from which synchronization information cannot be obtained directly or indirectly from the base station or GNSS. The synchronization source and preference are pre-set in the terminal. Alternatively, the synchronization source and preference are set by a control message provided by the base station.

[0094] The SL synchronization source is related to the priority of synchronization. For example, the relationship between the synchronization source and the priority of synchronization is defined as in Table 14 or Table 15. Tables 5 or 6 are just examples, and the relationship between the synchronization source and the synchronization priority can be defined in various ways.

[0095]

Table 5

[0096]

Table 6

[0097] In Table 5 or Table 6, P0 means the highest priority and P6 means the lowest priority. In Table 5 or Table 6, the base station includes at least one of gNB or eNB.

[0098] Whether to use GNSS-based synchronization or base-station-based synchronization is (pre-)set. In single-carrier operation, the terminal derives its transmission timing from the available synchronization reference with the highest priority.

[0099] Hereinafter, the sidelink synchronization signal (SLSS) and synchronization information will be described.

[0100] The SLSS includes, as an SL-specific sequence, a primary sidelink synchronization signal (PSSS) and a secondary sidelink synchronization signal (SSSS). The PSSS is called the sidelink primary synchronization signal (S-PSS), and the SSSS is called the sidelink secondary synchronization signal (S-SSS). For example, length-127 M-sequences are used for the S-PSS, and length-127 Gold sequences are used for the S-SSS. For example, the terminal detects the first signal using the S-PSS and acquires synchronization. For example, the terminal acquires detailed synchronization using the S-PSS and S-SSS and detects the synchronization signal ID.

[0101] The PSBCH (Physical Sidelink Broadcast Channel) is a (broadcast) channel through which the basic (system) information that a terminal should know first before SL signal transmission and reception is transmitted. For example, the basic information includes information related to SLSS, duplex mode (DM), TDD UL / DL (Time Division Duplex Uplink / Downlink) configuration, information related to resource pools, types of applications related to SLSS, subframe offset, broadcast information, etc. For example, in order to evaluate the performance of the PSBCH in NR V2X, the payload size of the PSBCH is 56 bits including a 24-bit CRC.

[0102] S-PSS, S-SSS, and PSBCH are included in a block format (e.g., SL SS (Synchronization Signal) / PSBCH block, hereinafter referred to as S-SSB (Sidelink-Synchronization Signal Block)) that supports periodic transmission. The S-SSB has the same numerology (i.e., SCS and CP length) as the PSCCH (Physical Sidelink Control Channel) / PSSCH (Physical Sidelink Shared Channel) within a carrier, and the transmission bandwidth is within a pre-set SL BWP (Sidelink BWP). For example, the bandwidth of the S-SSB is 11 RBs (Resource Blocks). For example, the PSBCH spans 11 RBs. Also, the frequency position of the S-SSB is pre-set. Therefore, the terminal does not need to perform hypothesis detection in terms of frequency to discover the S-SSB in a carrier.

[0103] On one hand, in the NR SL system, a plurality of numerologies having different SCSs and / or CP lengths are supported. At this time, as the SCS increases, the length of the time resource for the transmitting terminal to transmit the S-SSB becomes shorter. As a result, the coverage of the S-SSB is reduced. Therefore, in order to ensure the coverage of the S-SSB, the transmitting terminal transmits one or more S-SSBs to the receiving terminal within one S-SSB transmission period according to the SCS. For example, the number of S-SSBs transmitted by the transmitting terminal to the receiving terminal within one S-SSB transmission period is pre-configured or configured in the transmitting terminal. For example, the S-SSB transmission period is 160 ms. For example, a 160-ms S-SSB transmission period is supported for all SCSs.

[0104] For example, when the SCS is 15 kHz in FR1, the transmitting terminal transmits one or two S-SSBs to the receiving terminal within one S-SSB transmission period. For example, when the SCS is 30 kHz in FR1, the transmitting terminal transmits one or two S-SSBs to the receiving terminal within one S-SSB transmission period. For example, when the SCS is 60 kHz in FR1, the transmitting terminal transmits one, two, or four S-SSBs to the receiving terminal within one S-SSB transmission period.

[0105] FIG. 11 shows the procedure for a terminal to perform V2X or SL communication in the transmission mode according to an embodiment of the present invention. The embodiment of FIG. 11 can be combined with various embodiments of the present disclosure. In various embodiments of the present invention, the transmission mode is also called a mode or a resource allocation mode. Hereinafter, for the convenience of description, in LTE, the transmission mode is also called the LTE transmission mode, and in NR, the transmission mode is also called the NR resource allocation mode.

[0106] For example, FIG. 11(a) shows terminal operations related to LTE transmission mode 1 or LTE transmission mode 3. For example, FIG. 11(a) shows terminal operations 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.

[0107] For example, FIG. 11(b) shows terminal operations related to LTE transmission mode 2 or LTE transmission mode 4. Or for example, FIG. 11(b) shows terminal operations related to NR resource allocation mode 2.

[0108] Referring to FIG. 11(a), in LTE transmission mode 1, LTE transmission mode 3, or NR resource allocation mode 1, the base station schedules the SL resources used by the terminal for SL transmission. For example, in step S8000, the base station transmits information related to the SL resources and / or information related to the UL resources to the first terminal. For example, the UL resources include PUCCH resources and / or PUSCH resources. For example, the UL resources are resources for reporting SL HARQ feedback to the base station.

[0109] For example, the first terminal receives information regarding DG (dynamic grant) resources and / or information regarding CG (configured grant) resources from the base station. For example, the CG resources include CG type 1 resources or CG type 2 resources. In this specification, the DG resources are resources that the base station configures / allocates to the first terminal via DCI (downlink control information). In this specification, the CG resources are (periodic) resources that the base station configures / allocates to the first terminal via DCI and / or RRC messages. For example, in the case of CG type 1 resources, the base station transmits an RRC message including information regarding the CG resources to the first terminal. For example, in the case of CG type 2 resources, the base station transmits an RRC message including information regarding the CG resources to the first terminal, and the base station transmits DCI regarding activation or release of the CG resources to the first terminal.

[0110] In step S8010, the first terminal transmits a PSCCH (e.g., SCI (Sidelink Control Information) or 1st-stage SCI) to the second terminal based on resource scheduling. In step S8020, the first terminal transmits 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 receives a PSFCH related to the PSCCH / PSSCH from the second terminal. For example, HARQ feedback information (e.g., NACK information or ACK information) is received from the second terminal via the PSFCH. In step S8040, the first terminal transmits / reports the HARQ feedback information to the base station via the PUCCH or PUSCH. For example, the HARQ feedback information reported to the base station is information generated based on the HARQ feedback information received by the first terminal from the second terminal. For example, the HARQ feedback information reported to the base station is information generated by the first terminal based on a preset rule. For example, the DCI is DCI for SL scheduling. For example, the format of the DCI is DCI format 3_0 or DCI format 3_1. Table 7 shows an example of DCI for SL scheduling.

[0111]

Table 7

[0112] Referring to FIG. 11(b), in LTE transmission mode 2, LTE transmission mode 4, or NR resource allocation mode 2, the terminal determines the SL transmission resource within the SL resource set by the base station / network or the preset SL resource. For example, the set SL resource or the preset SL resource is a resource pool. For example, the terminal autonomously selects or schedules the resources for SL transmission. For example, the terminal selects the resources by itself within the set resource pool and performs SL communication. For example, the terminal performs the procedures of sensing and (re)selecting resources and selects the resources by itself within the selection window. For example, this sensing is performed on a subchannel basis. For example, in step S8010, the first terminal that has selected the resources by itself within the resource pool transmits the PSCCH (e.g., SCI (Sidelink Control Information) or 1st-stage SCI) to the second terminal using this resource. In step S8020, the first terminal transmits the PSSCH (e.g., 2nd-stage SCI, MAC PDU, data, etc.) related to the PSCCH to the second terminal. In step S8030, the first terminal receives the PSFCH related to the PSCCH / PSSCH from the second terminal.

[0113] Referring to FIG. 11(a) or (b), for example, the first terminal transmits an SCI to the second terminal on the PSCCH. Or, for example, the first terminal transmits two consecutive SCIs (e.g., 2-stage SCI) to the second terminal on the PSCCH and / or PSSCH. In this case, the second terminal decodes two consecutive SCIs (e.g., 2-stage SCI) to receive the PSSCH from the first terminal. In this specification, the SCI transmitted on the PSCCH is referred to as 1st SCI, the first SCI, 1st-stage SCI or 1st-stage SCI format, and the SCI transmitted on the PSSCH is referred to as 2nd SCI, the second SCI, 2nd-stage SCI or 2nd-stage SCI format. For example, the 1st-stage SCI format includes SCI format 1-A, and the 2nd-stage SCI format includes SCI format 2-A and / or SCI format 2-B. Table 8 shows an example of the 1st-stage SCI format.

[0114]

Table 8

[0115] Table 9 shows an example of the 2nd-stage SCI format.

[0116]

Table 9

[0117] Referring to FIG. 11(a) or (b), in step S8030, the first terminal receives the PSFCH based on Table 10. For example, the first terminal and the second terminal determine the PSFCH resource based on Table 10, and the second terminal transmits HARQ feedback to the first terminal using the PSFCH resource.

[0118]

Table 10

[0119] Referring to FIG. 11(a), in step S8040, the first terminal transmits SL HARQ feedback to the base station via PUCCH and / or PUSCH based on Table 11.

[0120]

Table 11

[0121] On the other hand, the following Table 12 shows the content related to the selection and reselection of sidelink relay UEs disclosed in 3GPP TS 36.331. The content of Table 12 is used as the prior art of the present invention, and for the details related thereto, refer to 3GPP TS 36.331.

[0122]

Table 12

[0123] FIG. 12 shows the process of connection management and direct-to-indirect path switching captured in the TR document (3GPP TR 38.836) related to Rel-17 NR SL. The remote UE needs to set up its PDU session / DRB with the network before transmitting user plane data.

[0124] The procedure for setting up the PC5 unicast link on the PC5-RRC aspect of Rel-16 NR V2X is reused for the remote UE to set up a secure unicast link for L2 UE-to-Network relaying between the remote UE and the relay UE before the remote UE establishes a Uu RRC connection with the network through the relay UE.

[0125] When the remote UE starts the first RRC message for connection setup with the gNB for both in-coverage and out-of-coverage, the PC5 L2 configuration for transmission between the remote UE and the UE-to-Network Relay UE is based on the RLC / MAC configuration defined in the standard. The establishment of the Uu SRB1 / SRB2 and DRB of the remote UE follows the procedures of the legacy Uu configuration for the L2 UE-to-Network Relay.

[0126] The high-level connection setup procedure shown in Figure 12 is applied to the L2 UE-to-Network Relay.

[0127] In step S1200, the remote and relay UEs perform a discovery procedure and set up a PC5-RRC connection in step S1201 based on the conventional Rel-16 procedure.

[0128] In step S1202, the remote UE uses the basic L2 configuration of PC5 to send the first RRC message (i.e., RRCSetupRequest) for connection setup with the gNB by the relay UE. The gNB responds to the remote UE with an RRC setup message (S1203). The transmission of RRCSetup to the remote UE uses the basic configuration of PC5. If the relay UE does not start from RRC_CONNECTED, it needs to perform its own connection setup when receiving a message for the basic L2 configuration of PC5. In this step, the details for the relay UE to transmit the RRCSetupRequest / RRCSetup message to the remote UE are discussed in the WI step.

[0129] In step S1204, the gNB and the relay UE perform a relay channel setup procedure over Uu. Depending on the configuration of the gNB, the relay / remote UE sets up an RLC channel for relaying SRB1 to the remote UE over PC5. This step prepares the relay channel for SRB1.

[0130] In step S1205, the remote UE SRB1 message (e.g., RRCSetupComplete message) is transmitted to the gNB via the relay UE using the SRB1 relay channel by PC5. Also, the remote UE is RRC-connected by Uu.

[0131] In step S1206, the remote UE and the gNB set up security according to the legacy procedure, and the security message is transmitted via the relay UE.

[0132] In step S1210, for traffic relay, the gNB further sets up an RLC channel between the gNB and the relay UE. Depending on the configuration of the gNB, the relay / remote UE further sets up an RLC channel between the remote UE and the relay UE for traffic relay. The gNB transmits RRCReconfiguration to the remote UE via the relay UE to set up the relay SRB2 / DRB. The remote UE transmits RRCReconfigurationComplete to the gNB via the relay UE as a response.

[0133] In the case of L2 UE-to-Network relay in addition to the connection setup procedure:

[0134] - The procedures for RRC reconfiguration and RRC connection release reuse the legacy RRC procedures together with the content / configuration design of the messages left in the WI step.

[0135] - The procedures for RRC connection reconfiguration and RRC connection resumption reuse the conventional RRC procedures as a baseline in consideration of the connection setup procedure of the aforementioned L2 UE-to-Network Relay to process the relay-specific parts together with the message content / configuration. The message content / configuration will be defined in the future. [[ID=2,4]]

[0136] Figure 13 shows an example of direct-to-indirect path switching. For the service continuity of the L2 UE-to-Network Relay, when the remote UE switches to the indirect relay UE, the procedure of Figure 13 is followed.

[0137] Referring to Figure 13, in step S1301, after the remote UE measures / discovers the candidate relay UE, the remote UE reports one or more candidate relay UEs. The remote UE filters the appropriate relay UE that meets the upper layer criteria at the time of reporting. The report includes the ID of the relay UE and the SL RSRP information, and hereafter, the details regarding the PC5 measurement are determined.

[0138] In step S1302, the gNB decides to switch to the target relay UE, and the target (re)configuration is selectively sent to the relay UE.

[0139] In step S1304, the RRC reconfiguration message for the remote UE includes the ID of the target relay UE, the target Uu, and the PC5 configuration.

[0140] In step S1305, if the connection has not been established yet, the remote UE sets up the connection with the target relay UE via PC5.

[0141] In step S1306, the remote UE uses the target configuration provided from the RRCReconfiguration to feedback the RRCReconfigurationComplete to the gNB via the target path.

[0142] In step S1307, the data path is switched.

[0143] The content of Tables 13 to 18 below is disclosed in the 3GPP TS 38.423 standard document related to handover and is used as the prior art of the content of this disclosure. In Table 14, Figure 8.2.1.2-1 corresponds to Figure 14, and for other matters, refer to the standard document 3GPP TS 38.423.

[0144]

Table 13-1

Table 13-2

[0145]

Table 14-1

Table 14-2

[0146]

Table 15-1

Table 15-2

[0147]

Table 16-1

Table 16-2

[0148]

Table 17-1

Table 17-2

[0149]

Table 18-1

Table 18-2

[0150] Based on Table 13 to Table 18 above, the HO process of a general UE is described as follows. The UE reports the Uu link measurement results (the Uu link signal strength of its serving cell and the Uu link signal strength of surrounding adjacent cells) to the base station, and the base station selects a target cell using the measurement results reported by the UE. The serving base station (Serving gNB) can request a HO request to the target base station (hereinafter, the target base station (target gNB)) to which the target cell belongs. When the target base station permits the HO, it transmits an RRCReconfiguration (withSync) message for the HO via the serving base station.

[0151] However, in the case of a remote UE, since it is connected to a relay UE, it is necessary to consider this point, which is different from the HO of a general UE. Since the remote UE can have not only a direct link but also an indirect link via the relay UE, problems such as which link of the direct link and the indirect link the relay UE should use after the handover, or who determines the direct link and the indirect link may arise. Hereinafter, embodiments related to such content will be disclosed in the present disclosure.

[0152] A source base station related to the handover (HO) of a remote user equipment (UE) according to an embodiment receives measurement results from the remote UE (S1501 in FIG. 15), and the source base station selects a target base station for the HO of the remote UE (S1502). Further, the source base station transmits a HO request message to the target base station (S1503).

[0153] Here, after the source base station decides to perform HO of the remote UE to the target base station, it determines whether to use an indirect path or a direct path. Alternatively, the source base station determines whether to use an indirect path or a direct path after the remote UE has handed over to the target base station. That is, the serving gNB can determine which of the direct link and the indirect link to select. This is because the source base station knows the measurement results between uu and the candidate relay UE, and it is most reasonable for the source base station other than the target base station to make the determination.

[0154] The HO request message includes information indicating one or more candidate relay UEs. That is, the HO request message includes a list consisting of one or more candidate relay UEs. The one or more candidate relay UEs belong to the target base station. After the remote UE hands over to the target base station, the relay UE is determined by the target base station from among the one or more candidate relay UEs. The information indicating the one or more candidate relay UEs is included in the HO request message based on the source base station's determination to use an indirect path after deciding to perform HO of the remote UE to the target base station.

[0155] That is, when the serving base station selects an indirect link and there are multiple candidate relay UEs belonging to the same cell (and / or the same gNB) corresponding thereto, the entity that selects the final relay UE may be the target base station. In this case, the serving base station can also send an HO request message to the target base station and notify all of the multiple candidate relay UEs belonging to the target base station.

[0156] The HO request message is one of the XnAP Handover Req and NGAP Handover Required messages.

[0157] The information indicating the one or more candidate relay UEs is transmitted by the source base station based on the determination that the remote UE will use an indirect path after handing over to the target base station.

[0158] Looking at the above-described embodiments from the perspective of the target base station, the target base station receives a HO request message including information indicating one or more candidate relay UEs from the source base station, and selects a relay UE from among the one or more candidate relay UEs. Further, the target base station transmits an RRCReconfiguration message to the remote UE. Here, the one or more candidate relay UEs belong to the target base station.

[0159] In the above description, the SL-RSRP (and / or SD-RSRP) measured for each candidate relay UE (and / or) the L2 ID of the candidate relay UE and the L2 ID of the remote UE may be notified to the target base station. That is, the information indicating the one or more candidate relay UEs includes one or more of the Sidelink Reference Signal Received Power (SL-RSRP) for each candidate relay UE, the Sidelink discovery RSRP (SD-RSRP), the L2 ID of the candidate relay UE, and the L2 ID of the remote UE.

[0160] Alternatively, when the serving base station transmits a HO request message to the target base station, the above-described L2 ID of the remote UE, the L2 ID(s) of the candidate relay UE(s), the SL signal strength measurement value (and / or SD-RSRP), etc. are transmitted together. That is, the HO request message includes one or more of the Sidelink Reference Signal Received Power (SL-RSRP) for each candidate relay UE, the Sidelink discovery RSRP (SD-RSRP), the L2 ID of the candidate relay UE, and the L2 ID of the remote UE.

[0161] Alternatively, the L2 ID of the remote UE, the L2 ID(s) of the candidate relay UE(s), the SL signal strength measurement value (and / or SD-RSRP), etc. are transmitted via the Xn interface between the serving base station and the target base station. That is, the serving base station transmits, via the Xn interface to the target base station, one or more of the sidelink reference signal received power (SL-RSRP), sidelink discovery RSRP (SD-RSRP), the L2 ID of the candidate relay UE, and the L2 ID of the remote UE for each candidate relay UE.

[0162] After that, the source base station transmits the RRCReconfiguration message sent by the target base station to the remote UE.

[0163] As described above, the remote UE measures the direct link and the indirect link and reports them to its serving base station. At this time, the remote UE reports its L2 ID and the L2 ID of the candidate relay UE together with the measurement results to the serving base station. The serving gNB can determine which of the direct link and the indirect link to select. When the indirect link is selected, the serving base station transmits a handover request (e.g., XnAP Handover Req, NGAP Handover Required message) to the base station of the cell to which the selected relay UE belongs (target base station).

[0164] At this time, the serving base station transmits the L2 ID of the remote UE, the selected relay UE L2 ID (and / or) SL-RSRP (and / or) SD-RSRP measurement results to the target base station. Further, it transmits the signal strength of the direct link between the current remote UE and the serving cell to the target base station. If the relay UE existing in the target cell is in the RRC_CONNECTED state, it should have reported its SRC L2 ID to the base station. Therefore, the target base station uses the L2 ID of the candidate relay UE notified by the serving base station to identify which UE the relay UE is. As a result, when the target base station transmits a message allowing HO to the serving base station, it performs settings (bearer settings, bearer mapping, local / temporal ID assignment, etc.) for connecting the selected relay UE to the remote UE. If the relay UE existing in the target cell is in the RRC_IDLE / INACTIVE state, the target base station cannot identify the L2 ID of the candidate relay UE notified by the serving base station, but it can select it as the UE to be used during HO.

[0165] Also, the serving base station knows the cell (and / or gNB) value to which the candidate relay UE belongs, but does not know the RRC state of the candidate relay UE, the Uu link signal strength between the candidate relay UE and the target base station, etc. Therefore, if the target base station is notified of the candidate relay UE ID belonging to the target base station and the SL measurement result (e.g., SD-RSRP), or further the Uu link signal strength between the serving gNB and the remote UE, the target base station can make a more optimized selection considering the RRC state and Uu link signal strength of the candidate relay UE. Also, when the selected relay UE is in RRC CONNECTED, settings for HO are pre-assigned, so there is a gain (from the perspective of latency). Also, by notifying the target base station of the L2 ID of the remote UE, the target base station can enable settings for HO for the relay UE, particularly local / temporal ID assignment, etc.

[0166] In relation to the foregoing description, the source base station includes at least one processor and at least one computer memory operably coupled to the at least one processor and storing instructions that, when executed, cause the at least one processor to perform operations, the operations including the source base station receiving measurement results from the remote UE, the source base station selecting a target base station for HO of the remote UE, and the source base station transmitting an HO request message to the target base station, and the source base station is a UE that determines whether to use an indirect path or a direct path after determining to perform HO of the remote UE to the target base station.

[0167] The remote UE communicates with at least one of other UEs, UEs related to autonomous vehicles, base stations, or networks.

[0168] Also, a non-volatile computer-readable storage medium storing at least one computer program that, when executed by at least one processor, causes the at least one processor to perform operations for a source base station, the operations including the source base station receiving measurement results from a remote UE, the source base station selecting a target base station for handover (HO) of the remote UE, and the source base station transmitting an HO request message to the target base station, and after the source base station determines to perform HO of the remote UE to the target base station, determining whether to use an indirect path or a direct path.

[0169] Also, a target base station including at least one processor and at least one computer memory operably coupled to the at least one processor and storing instructions that, when executed, cause the at least one processor to perform operations, the operations including the target base station receiving an HO request message including information indicating one or more candidate relay UEs from a source base station, the target base station selecting a relay UE from among the one or more candidate relay UEs, and the target base station transmitting an RRCReconfiguration message to the remote UE, and the one or more candidate relay UEs belong to the target base station.

[0170] As another example, the target base station can determine which link to select between a direct link and an indirect link. Specifically, the remote UE measures the direct link and the indirect link and reports them to its serving base station. At this time, the remote UE reports its L2 ID and the L2 ID of the candidate relay UE to the serving base station together with the measurement results. The target base station can determine which link to select between the direct link and the indirect link. When the target base station determines the direct link and the indirect link, the serving base station first needs to determine the target base station. The method for the serving gNB to determine the target base station is as follows.

[0171] - Select the best cell based on the direct link. Select the base station to which the best cell belongs as the target base station.

[0172] - Select the best candidate relay UE based on the indirect link. Select the base station of the cell to which the selected candidate relay UE belongs as the target base station.

[0173] - Select based on the preference (and / or capability) of the remote UE. For example, if the remote UE prefers the indirect link more, select the best candidate relay UE based on the indirect link, and select the base station of the cell to which the selected candidate relay UE belongs as the target base station.

[0174] - If the remote UE prefers the direct link more, select the target cell based on the direct link, and select the base station of the cell to which the target cell belongs as the target base station.

[0175] After selecting the target base station, the serving base station transmits to the target base station the signal strength of the direct link (the signal strength of the direct link between the current serving cell and the remote UE (and / or) the signal strength of the direct link with the target cell), the L2 ID of the candidate relay UE belonging to the target base station, the L2 ID of the remote UE, the measured SL signal (s) strength (such as SD-RSRP) between the candidate relay UE(s) and the remote UE (and / or) the capability of the remote UE, the link preference of the remote UE (such as whether to prefer the direct link or the indirect link), etc. together with the HO request message to the target base station.

[0176] The target base station that receives this selects a link for the remote UE (e.g., a direct link or an indirect link). If the target base station selects an indirect link and HO is allowed, it includes the L2 ID of the selected relay UE in the RRCReconfiguration(withSync) message for the configuration of the HO operation and transmits it to the remote UE via the serving base station.

[0177] When the serving base station of the remote UE determines the target gNB, not only the Uu signal strength of the target gNB measured by the remote UE, but also whether the target base station / target cell has the serving base station / serving cell, or information about candidate relay UEs (e.g., L2 ID of the relay UE, SD-RSRP, serving cell / PLMN of the relay UE) among the relay UEs camping on the target base station / cell with an SL signal strength equal to or greater than a threshold is transmitted to the target gNB. At this time, the candidate relay UEs transmitted to the target gNB by the source gNB can be limited to those whose SL signal strength exceeds the set threshold.

[0178] When the source gNB selects one of the candidate relay UEs (including the information of the selected relay UE) and requests the target gNB for HO, the signal strength of the direct link measured by the remote UE can be transmitted together. At this time, the signal strength of the direct link is the signal strength with respect to the serving cell / gNB or the camping-on cell / gNB of the relay UE selected by the source gNB. This Uu signal strength is notified to the target gNB together with the selected relay UE only when the measured value exceeds the set threshold. If it is less than the set threshold, the reporting of the measured value may be omitted. The information is included in the HO request message transmitted by the source gNB to the target gNB.

[0179] The L2 ID of the aforementioned remote UE, the L2 ID(s) of the candidate relay UE(s), the measured value of the SL signal strength (and / or SD-RSRP), the signal strength of the current direct link, the signal strength of the direct link measured for the target cell, etc. are transmitted via the Xn interface between the serving base station and the target base station. When the serving base station transmits a HO request message to the target base station, the L2 ID of the aforementioned remote UE, the L2 ID(s) of the candidate relay UE(s), the measured value of the SL signal strength (and / or SD-RSRP), etc. are transmitted together. The aforementioned serving base station is replaced by the serving cell, and the target base station is replaced by the target cell.

[0180] The aforementioned candidate relay UE(s) can mean a plurality of candidate relay UEs.

[0181] Example of a communication system to which the present invention is applied

[0182] Although not limited thereto, the various descriptions, functions, procedures, proposals, methods, and / or flowcharts of the present invention disclosed in this specification can be applied to various fields that require wireless communication / connection between devices (e.g., 5G).

[0183] Hereinafter, a more specific description will be given with reference to the drawings. In the following figures / descriptions, the same reference numerals exemplify the same or corresponding hardware blocks, software blocks, or functional blocks unless otherwise particularly mentioned.

[0184] FIG. 16 illustrates a communication system 1 to which the present invention is applied.

[0185] Referring to FIG. 16, the communication system 1 applied to the present invention includes a wireless device, a base station, and a network. Here, the wireless device means a device that communicates using a wireless connection technology (for example, 5G NR, LTE), and is also referred to as a communication / wireless / 5G device. Without being limited thereto, the wireless devices include a robot 100a, vehicles 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 includes a vehicle equipped with a wireless communication function, an autonomous driving vehicle, a vehicle capable of vehicle-to-vehicle communication, etc. Here, the vehicle includes a UAV (Unmanned Aerial Vehicle) (for example, a drone). The XR device includes an AR (Augmented Reality) / VR (Virtual Reality) / MR (Mixed Reality) device, and is embodied in the form of an HMD (Head-Mounted Device), a HUD (Head-Up Display) provided in a vehicle, a TV, a smartphone, a computer, a wearable device, a home appliance, a digital signboard, a vehicle, a robot, etc. The hand-held device includes a smartphone, a smart pad, a wearable device (for example, a smartwatch, smart glasses), a computer (for example, a notebook personal computer, etc.). The home appliance includes a TV, a refrigerator, a washing machine, etc. The IoT device includes a sensor, a smart meter, etc. For example, the base station and the network are also embodied in the wireless device, and a specific wireless device 200a can also operate as a base station / network node for other wireless devices.

[0186] Wireless devices 100a to 100f are connected to network 300 via base station 200. AI (Artificial Intelligence) technology is applied to wireless devices 100a to 100f, and wireless devices 100a to 100f are connected to AI server 400 via network 300. Network 300 is configured using a 3G network, a 4G (e.g., LTE) network, a 5G (e.g., NR) network, or the like. Wireless devices 100a to 100f can communicate with each other via base station 200 / network 300, but can also communicate directly without going through the base station / network (e.g., sidelink communication). For example, vehicles 100b-1 and 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.

[0187] Wireless communications / connections 150a, 150b, and 150c are performed between wireless devices 100a to 100f / base station 200 and between base stations 200 / 200. Here, the wireless communications / connections are uplink / downlink communication 150a, sidelink communication 150b (or D2D communication), and inter-base station communication 150c (e.g., performed by various wireless connection technologies such as relay, IAB (Integrated Access Backhaul) (e.g., 5G NR)). Through wireless communications / connections 150a, 150b, and 150c, wireless devices and base stations / wireless devices, and base stations and base stations can send / receive wireless signals to / from each other. For example, wireless communications / connections 150a, 150b, and 150c can send / receive signals via various physical channels. For this purpose, based on various proposals of the present invention, any one of the setting process of various configuration information for sending / receiving wireless signals, various signal processing processes (e.g., channel encoding / decoding, modulation / demodulation, resource mapping / demapping, etc.), and resource allocation process is performed.

[0188] Examples of wireless devices to which the present invention is applied

[0189] FIG. 17 illustrates a wireless device to which the present invention is applied.

[0190] Referring to FIG. 17, the first wireless device 100 and the second wireless device 200 transmit and receive wireless signals by various wireless connection technologies (e.g., LTE, NR). Here, {the first wireless device 100, the second wireless device 200} corresponds to {the wireless device 100x, the base station 200} and / or {the wireless device 100x, the wireless device 100x} in FIG. 21.

[0191] The first wireless device 100 includes one or more processors 102 and one or more memories 104, and further includes one or more transceivers 106 and / or one or more antennas 108. The processor 102 controls the memory 104 and / or the transceiver 106, and is configured to implement the descriptions, functions, procedures, proposals, methods, and / or flowcharts disclosed in this specification. For example, after the processor 102 processes the information in the memory 104 to generate a first information / signal, the transceiver 106 transmits a wireless signal including the first information / signal. Also, after the processor 102 receives a wireless signal including a second information / signal by the transceiver 106, the information obtained from the signal processing of the second information / signal is stored in the memory 104. The memory 104 is connected to the processor 102 and stores various information related to the operation of the processor 102. For example, the memory 104 stores software code including instructions for performing part or all of the processes controlled by the processor 102, or for performing the descriptions, functions, procedures, proposals, methods, and / or flowcharts disclosed in this specification. Here, the processor 102 and the memory 104 are part of a communication modem / circuit / chip designed to implement wireless communication technologies (e.g., LTE, NR). The transceiver 106 is connected to the processor 102 and transmits and / or receives wireless signals through one or more antennas 108. The transceiver 106 includes a transmitter and / or a receiver. The transceiver 106 can also be used interchangeably with an RF (radio Frequency) unit. In the present invention, the wireless device can also mean a communication modem / circuit / chip.

[0192] The second wireless device 200 includes one or more processors 202 and one or more memories 204, and further includes one or more transceivers 206 and / or one or more antennas 208. The processor 202 controls the memory 204 and / or the transceiver 206, and is configured to implement the descriptions, functions, procedures, proposals, methods, and / or flowcharts disclosed in this specification. For example, after the processor 202 processes the information in the memory 204 to generate third information / signals, the transceiver 206 transmits a wireless signal including the third information / signals. Also, after the processor 202 receives a wireless signal including fourth information / signals by the transceiver 206, the information obtained from the signal processing of the fourth information / signals is stored in the memory 204. The memory 204 is connected to the processor 202 and stores various information related to the operation of the processor 202. For example, the memory 204 stores software code including instructions for performing some or all of the processes controlled by the processor 202, or for performing the descriptions, functions, procedures, proposals, methods, and / or flowcharts disclosed in this specification. Here, the processor 202 and the memory 204 are part of a communication modem / circuit / chip designed to implement wireless communication technologies (e.g., LTE, NR). The transceiver 206 is connected to the processor 202 and transmits and / or receives wireless signals through one or more antennas 208. The transceiver 206 includes a transmitter and / or a receiver. The transceiver 206 can also be used interchangeably with an RF unit. In the present invention, the wireless device can also mean a communication modem / circuit / chip.

[0193] The hardware elements of wireless devices 100 and 200 will be described in more detail below. Although not limited thereto, one or more protocol layers are implemented by one or more processors 102 and 202. For example, one or more processors 102 and 202 implement one or more layers (e.g., functional layers such as PHY, MAC, RLC, PDCP, RRC, SDAP). One or more processors 102 and 202 generate one or more PDUs (Protocol Data Units) and / or one or more SDUs (Service Data Units) according to the descriptions, functions, procedures, proposals, methods, and / or flowcharts disclosed in this specification. One or more processors 102 and 202 generate messages, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and / or flowcharts disclosed in this specification. One or more processors 102 and 202 generate a signal (e.g., a baseband signal) including PDUs, SDUs, messages, control information, data, or information according to the functions, procedures, proposals, and / or methods disclosed in this specification and provide it to one or more transceivers 106 and 206. One or more processors 102 and 202 receive a signal (e.g., a baseband signal) from one or more transceivers 106 and 206 and can obtain PDUs, SDUs, messages, control information, data, or information according to the descriptions, functions, procedures, proposals, methods, and / or flowcharts disclosed in this specification.

[0194] One or more processors 102, 202 are also referred to as a controller, a microcontroller, a microprocessor, or a microcomputer. One or more processors 102, 202 are implemented by hardware, firmware, software, or a combination thereof. As an example, one or more ASICs (Application Specific Integrated Circuits), one or more DSPs (Digital Signal Processors), one or more DSPDs (Digital Signal Processing Devices), one or more PLDs (Programmable Logic Devices), or one or more FPGAs (Field Programmable Gate Arrays) are included in one or more processors 102, 202. The descriptions, functions, procedures, proposals, methods, and / or flowcharts disclosed in this specification are implemented using firmware or software, and the firmware or software is implemented to include modules, procedures, functions, and the like. The firmware or software configured to perform the descriptions, functions, procedures, proposals, methods, and / or flowcharts disclosed in this specification is included in one or more processors 102, 202, or stored in one or more memories 104, 204 and driven by one or more processors 102, 202. The descriptions, functions, procedures, proposals, methods, and / or flowcharts disclosed in this specification are implemented using firmware or software in the form of code, instructions, and / or sets of instructions.

[0195] One or more memories 104, 204 are connected to one or more processors 102, 202 and store various forms of data, signals, messages, information, programs, codes, instructions, and / or commands. The one or more memories 104, 204 are composed of ROM, RAM, EPROM, flash memory, hard drive, register, cache memory, computer-readable storage medium, and / or combinations thereof. The one or more memories 104, 204 are located inside and / or outside the one or more processors 102, 202. Also, the one or more memories 104, 204 are connected to the one or more processors 102, 202 by various techniques such as wired or wireless connection.

[0196] One or more transceivers 106, 206 can transmit user data, control information, radio signals / channels, etc. mentioned in this specification and / or in a flowchart, etc. to one or more other devices. One or more transceivers 106, 206 can receive user data, control information, radio signals / channels, etc. mentioned in the descriptions, functions, procedures, proposals, methods, and / or flowcharts, etc. disclosed in this specification from one or more other devices. For example, one or more transceivers 106, 206 are connected to one or more processors 102, 202 and transmit and receive radio signals. For example, one or more processors 102, 202 can control one or more transceivers 106, 206 to transmit user data, control information, or radio signals to one or more other devices. Also, one or more processors 102, 202 can control one or more transceivers 106, 206 to receive user data, control information, or radio signals from one or more other devices. One or more transceivers 106, 206 are connected to one or more antennas 108, 208, and one or more transceivers 106, 206 are configured to transmit and receive user data, control information, radio signals / channels, etc. mentioned in the descriptions, functions, procedures, proposals, methods, and / or flowcharts, etc. disclosed in this specification by one or more antennas 108, 208. In this specification, one or more antennas are multiple physical antennas or multiple logical antennas (e.g., antenna ports). One or more transceivers 106, 206 convert received radio signals / channels, etc. from RF band signals to baseband signals (Convert) in order to process the received user data, control information, radio signals / channels, etc. using one or more processors 102, 202. One or more transceivers 106, 206 convert user data, control information, radio signals / channels, etc. processed using one or more processors 102, 202 from baseband signals to RF band signals. For this purpose, one or more transceivers 106, 206 include (analog) oscillators and / or filters.

[0197] Examples of vehicles or autonomous vehicles to which the present invention is applied

[0198] FIG. 18 illustrates a vehicle or an autonomous vehicle to which the present invention is applied. The vehicle or the autonomous vehicle is embodied as a mobile robot, a vehicle, a train, an aerial vehicle (AV), a ship, or the like.

[0199] Referring to FIG. 18, the vehicle or the autonomous vehicle 100 includes 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 is part of the communication unit 110.

[0200] The communication unit 110 transmits and receives signals (e.g., data, control signals, etc.) to and from external devices such as other vehicles, base stations (e.g., base stations, roadside units), servers, etc. The control unit 120 controls the elements of the vehicle or the autonomous vehicle 100 to perform various operations. The control unit 120 includes an ECU (Electronic Control Unit). The vehicle or the autonomous vehicle 100 travels on the ground by the driving unit 140a. The driving unit 140a includes an engine, a motor, a power train, wheels, brakes, a steering device, and the like. The power supply unit 140b supplies power to the vehicle or the autonomous vehicle 100 and includes a wired / wireless charging circuit, a battery, and the like. The sensor unit 140c can obtain vehicle state, surrounding environment information, user information, etc. The sensor unit 140c includes an IMU (Inertial Measurement Unit) sensor, a collision sensor, a wheel sensor, a speed sensor, an inclination sensor, a weight sensing 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, an illuminance sensor, a pedal position sensor, and the like. The autonomous driving unit 140d embodies technologies such as maintaining the lane during driving, automatically adjusting the speed like an adaptive cruise control, automatically driving along a predetermined route, and setting and driving along a route automatically when a destination is set.

[0201] As an example, the communication unit 110 receives map data, traffic information data, etc. from an external server. The autonomous driving unit 140d generates an autonomous driving route and a drive plan based on the obtained data. The control unit 120 controls the drive unit 140a so that the vehicle or the autonomous driving vehicle 100 moves along the autonomous driving route according to the drive plan (for example, speed / direction adjustment). The communication unit 110 periodically obtains the latest traffic information data from the external server during autonomous driving, and also obtains the surrounding traffic information data from the surrounding vehicles. In addition, the sensor unit 140c obtains the vehicle state and the surrounding environment information during autonomous driving. The autonomous driving unit 140d updates the autonomous driving route and the drive plan based on the newly obtained data / information. The communication unit 110 transmits information regarding the vehicle position, the autonomous driving route, the drive plan, etc. to the external server. The external server can predict the traffic information data in advance using AI technology, etc. based on the information collected from the vehicle or the autonomous driving vehicle, and provide the predicted traffic information data to the vehicle or the autonomous driving vehicle.

[0202] Examples of AR / VR and vehicles to which the present invention is applied

[0203] FIG. 19 illustrates a vehicle to which the present invention is applied. The vehicle can also be embodied in a transportation means, a train, an aircraft, a ship, etc.

[0204] Referring to FIG. 19, the vehicle 100 includes a communication unit 110, a control unit 120, a memory unit 130, an input / output unit 140a, and a position measurement unit 140b.

[0205] The communication unit 110 transmits and receives signals (e.g., data, control signals, etc.) to and from external devices such as other vehicles or base stations. The control unit 120 can control the components of the vehicle 100 to perform various operations. The memory unit 130 stores data / parameters / programs / codes / instructions that support various functions of the vehicle 100. The input / output unit 140a outputs AR / VR objects based on the information in the memory unit 130. The input / output unit 140a includes a HUD. The position measurement unit 140b can obtain the position information of the vehicle 100. The position information includes the absolute position information of the vehicle 100, the position information within the driving lane, acceleration information, the position information with respect to surrounding vehicles, etc. The position measurement unit 140b includes GPS and various sensors.

[0206] As an example, the communication unit 110 of the vehicle 100 receives map information, traffic information, etc. from an external server and stores them in the memory unit 130. The position measurement unit 140b obtains vehicle position information by means of GPS and various sensors and stores it in the memory unit 130. The control unit 120 generates a virtual object based on the map information, traffic information, and vehicle position information, etc., and the input / output unit 140a displays the generated virtual object on the window inside the vehicle (1410, 140a). Also, the control unit 120 determines whether the vehicle 100 is operating correctly within the driving lane based on the vehicle position information. When the vehicle 100 deviates from the driving lane abnormally, the control unit 120 causes the input / output unit 140a to display a warning on the window inside the vehicle. Also, the control unit 120 broadcasts a warning message regarding abnormal driving to the surrounding vehicles through the communication unit 110. Depending on the situation, the control unit 120 can also transmit the vehicle's position information and information regarding driving / vehicle abnormalities to the relevant authorities through the communication unit 110.

[0207] Examples of XR devices to which the present invention is applied

[0208] FIG. 20 illustrates an XR device to which the present invention is applied. The XR device is embodied in the form of an HMD, a HUD (Head-Up Display) installed in a vehicle, a TV, a smartphone, a computer, a wearable device, a home appliance, a digital signboard, a vehicle, a robot, etc.

[0209] Referring to FIG. 20, the XR device 100a includes 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.

[0210] The communication unit 110 can transmit and receive signals (such as media data, control signals, etc.) with external devices such as other wireless devices, mobile devices, or media servers. The media data includes video, images, sounds, etc. The control unit 120 controls the components of the XR device 100a to perform various operations. For example, the control unit 120 is configured to control and / or perform procedures such as video / image acquisition, (video / image) encoding, metadata generation and processing. The memory unit 130 stores data / parameters / programs / codes / instructions necessary for driving the XR device 100a / generating XR objects. The input / output unit 140a obtains control information, data, etc. from the outside and outputs the generated XR objects. The input / output unit 140a includes a camera, a microphone, a user input unit, a display unit, a speaker, and / or a haptic module, etc. The sensor unit 140b obtains XR device status, surrounding environment information, user information, etc. The sensor unit 140b includes 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, an optical sensor, a microphone, and / or a radar, etc. The power supply unit 140c supplies power to the XR device 100a and includes a wired / wireless charging circuit, a battery, etc.

[0211] As an example, the memory unit 130 of the XR device 100a contains information (such as data, etc.) necessary for the generation of XR objects (for example, AR / VR / MR objects). The input / output unit 140a can obtain instructions for operating the XR device 100a from the user, and the control unit 120 drives the XR device 100a according to the user's driving instructions. For example, when the user watches a movie, news, etc. using the XR device 100a, the control unit 120 can transmit content request information to other devices (such as the mobile device 100b) or a media server through the communication unit 130. The communication unit 130 can download / stream content such as movies and news from other devices (such as the 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 on the content, and generates / outputs XR objects based on information about the surrounding space or real objects obtained by the input / output unit 140a / sensor unit 140b.

[0212] The XR device 100a is wirelessly connected to the mobile device 100b by the communication unit 110, and the operation of the XR device 100a is controlled by the mobile device 100b. For example, the mobile device 100b operates as a controller for the XR device 100a. For this purpose, after obtaining the three-dimensional position information of the mobile device 100b, the XR device 100a can generate and output an XR entity corresponding to the mobile device 100b.

[0213] Examples of robots to which the present invention is applied

[0214] FIG. 21 illustrates a robot to which the present invention is applied. Robots can be classified into industrial, medical, household, military, etc. according to their usage purposes and fields.

[0215] Referring to FIG. 21, the robot 100 includes 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.

[0216] The communication unit 110 transmits and receives signals (such as drive information, control signals, etc.) with external devices such as other wireless devices, other robots, or control servers. The control unit 120 can control the components of the robot 100 to perform various operations. The memory unit 130 stores data / parameters / programs / codes / instructions that support various functions of the robot 100. The input / output unit 140a obtains information from outside the robot 100 and outputs information to the outside of the robot 100. The input / output unit 140a includes a camera, a microphone, a user input unit, a display unit, a speaker, and / or a haptics module, etc. The sensor unit 140b obtains internal information of the robot 100, surrounding environment information, user information, etc. The sensor unit 140b includes 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, an optical sensor, a microphone, a radar, etc. The drive unit 140c performs various physical operations such as moving the robot joints. Also, the drive unit 140c can make the robot 100 travel on the ground or fly in the air. The drive unit 140c includes an actuator, a motor, wheels, brakes, a propeller, etc.

[0217] Examples of AI devices to which the present invention is applied

[0218] Referring to FIG. 22, the AI device is exemplified. The AI device is embodied in fixed devices or movable devices such as a TV, a projector, a smartphone, a PC, a notebook computer, a digital broadcast terminal, a tablet PC, a wearable device, a set-top box (STB), a radio, a washing machine, a refrigerator, digital signage, a robot, a vehicle, etc.

[0219] Referring to FIG. 22, the AI device 100 includes a communication unit 110, a control unit 120, a memory unit 130, input / output units 140a / 140b, a running processor unit 140c, and a sensor unit 140d.

[0220] The communication unit 110 transmits and receives wired / wireless signals (such as sensor information, user input, learning models, control signals, etc.) to / from external devices such as other AI devices (e.g., 100x, 200, 400 in FIG. 16) and AI servers (e.g., 400 in FIG. 16) using wired / wireless communication technologies. For this purpose, the communication unit 110 transmits the information in the memory unit 130 to an external device or transmits the signal received from an external device to the memory unit 130.

[0221] Based on the information determined or generated using a data analysis algorithm or a machine learning algorithm, the control unit 120 determines one executable operation of the AI device 100. Also, the control unit 120 can control the components of the AI device 100 to perform the determined operation. For example, the control unit 120 can request, search, receive, or utilize the data of the running processor unit 140c or the memory unit 130, and control the components of the AI device 100 to execute the predicted operation or the operation determined to be desirable among the executable operations. Further, the control unit 120 can collect the history information including the operation content of the AI device 100 and the user feedback on the operation, and store it in the memory unit 130 or the running processor unit 140c, or transmit it to an external device such as an AI server (FIG. 17, 400). The collected history information is used when updating the learning model.

[0222] The memory unit 130 stores data that supports various functions of the AI device 100. For example, the memory unit 130 stores the data obtained from the input unit 140a, the data obtained from the communication unit 110, the output data of the running processor unit 140c, and the data obtained from the sensing unit 140. Also, the memory unit 130 stores the control information and / or software code necessary for the operation / execution of the control unit 120.

[0223] The input unit 140a obtains various types of data from outside the AI device 100. For example, the input unit 140a obtains training data for model learning, input data to which the learned model is applied, and the like. The input unit 140a includes a camera, a microphone, and / or a user input unit, etc. The output unit 140b generates outputs related to vision, audition, or tactile sensation, etc. The output unit 140b includes a display unit, a speaker, and / or a haptics module, etc. The sensing unit 140 obtains any one of the internal information of the AI device 100, the surrounding environment information of the AI device 100, and user information by using various sensors. The sensing unit 140 includes 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, an optical sensor, a microphone, and / or a radar, etc.

[0224] The running processor unit 140c learns a model composed of an artificial neural network by using training data. The running processor unit 140c performs AI processing together with the running processor unit of the AI server (FIG. 17, 400). The running processor unit 140c processes the information received from an external device by the communication unit 110 and / or the information stored in the memory unit 130. Also, the output value of the running processor unit 140c is transmitted to an external device by the communication unit 110 or stored in the memory unit 130.

Industrial Applicability

[0225] The above embodiment can be applied to various mobile communication systems.

Claims

1. In a wireless communication system, a method for operating a source base station related to handover (HO) of a remote user equipment (User Equipment (UE)), comprising: the source base station receives measurement results from the remote UE; the source base station selects a target base station for HO of the remote UE; the source base station transmits a HO request message to the target base station; wherein the HO request message includes information indicating one or more candidate relay UEs; the one or more candidate relay UEs belong to the target base station.

2. The method according to claim 1, wherein after the source base station determines to perform HO of the remote UE to the target base station, the source base station determines whether to use an indirect path or a direct path.

3. The method according to claim 1, wherein the information indicating the one or more candidate relay UEs is included in the HO request message based on the source base station's determination to use an indirect path after determining to perform HO of the remote UE to the target base station.

4. The method according to claim 1, wherein the information indicating the one or more candidate relay UEs is transmitted based on the source base station's determination to use an indirect path after the remote UE has been handed over to the target base station.

5. The method according to claim 1, wherein the information indicating the one or more candidate relay UEs includes one or more of side link reference signal received power (SL-RSRP) for each candidate relay UE, side link discovery RS received power (SD-RSRP), L2 ID of the candidate relay UE, and L2 ID of the remote UE.

6. The method according to claim 1, wherein the HO request message includes one or more of side link reference signal received power (SL-RSRP) for each candidate relay UE, side link discovery RS received power (SD-RSRP), L2 ID of the candidate relay UE, and L2 ID of the remote UE.

7. The serving base station transmits, to the target base station via an Xn interface, one or more of the sidelink reference signal reception power (SL-RSRP), sidelink discovery RSRP (SD-RSRP), L2 ID of a candidate relay UE, and L2 ID of a remote UE for each candidate relay UE. The method according to claim 1.

8. The source base station transmits the RRCReconfiguration message transmitted by the target base station to the remote UE. The method according to claim 1.

9. The HO request message is one of an XnAP Handover Req and an NGAP Handover Required message. The method according to claim 1.

10. In a radio communication system, a method for operating a target base station related to handover (HO) of a remote user equipment (UE), the target base station receives an HO request message including information indicating one or more candidate relay UEs from a source base station, the target base station selects a relay UE from among the one or more candidate relay UEs, the target base station transmits an RRCReconfiguration message to the remote UE, including, the one or more candidate relay UEs belong to the target base station. The method.

11. In a radio communication system, a target base station, at least one processor, at least one computer memory operably coupled to the at least one processor and storing instructions that, when executed, cause the at least one processor to perform operations, the operations include, the target base station receives an HO request message including information indicating one or more candidate relay UEs from a source base station, the target base station selects a relay UE from among the one or more candidate relay UEs, the target base station transmits an RRCReconfiguration message to the remote UE, including, the one or more candidate relay UEs belong to the target base station. The target base station.

Images