Techniques for conditional handover of remote and relay user equipment

Abstract

Aspects of the disclosure provide techniques for configuring and triggering a conditional handover between a direct connection (Uu connection) and / or a relayed connection (PC5 connection) to a base station for UE mobility. Specifically, a conditional handover configuration can include preparing multiple candidate relay UEs for a handover (e.g., from a Uu connection to a PC5 connection) and conditional handover execution criteria for a UE to make a relay selection (or reselection). Similarly, features of the disclosure provide techniques for conditionally transitioning back to a Uu connection from a PC5 connection when the conditional handover execution criteria are met (e.g., a sidelink signal strength between two UEs drops below a channel condition threshold). Additionally, techniques provided herein support conditionally handing over a relay UE from a first base station to a second base station when the relay UE also supports one or more remote UEs.

Description

Technical Field

[0001] This disclosure relates to wireless communication systems, and more particularly to techniques for conditional handover of remote and relay user equipment (UE).

[0002] background

[0003] Wireless communication systems are widely deployed to provide a variety of telecommunications services such as telephone, video, data, messaging, and broadcasting. Typical wireless communication systems employ multiple access technologies that enable communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power). Examples of such multiple access technologies include Code Division Multiple Access (CDMA) systems, Time Division Multiple Access (TDMA) systems, Frequency Division Multiple Access (FDMA) systems, Orthogonal Frequency Division Multiple Access (OFDMA) systems, and Single Carrier Frequency Division Multiple Access (SC-FDMA) systems.

[0004] These multiple access technologies have been adopted in various telecommunications standards to provide a common protocol enabling different wireless devices to communicate at the city, national, regional, and even global levels. For example, fifth-generation (5G) wireless communication technology (which may be referred to as New Radio (NR)) is designed to expand and support a diverse range of use cases and applications relative to current mobile network generations. In one aspect, 5G communication technologies can include: enhanced mobile broadband for human-centric use cases of accessing multimedia content, services, and data; ultra-reliable low latency communication (URLLC) with certain specifications regarding latency and reliability; and massive machine-type communication, which allows for a very large number of connected devices and the transmission of relatively small amounts of non-latency-sensitive information. However, with the continued growth in demand for mobile broadband access, further improvements to NR and ultra-NR communication technologies may be expected.

[0005] Overview

[0006] This disclosure provides techniques for configuring and triggering conditional handover for UE mobility between direct connections (Uu connections) and / or relay connections (PC5 connections) to a base station. Specifically, conditional handover configuration may include multiple candidate relay UEs prepared for handover (e.g., from a Uu connection to a PC5 connection) and conditional handover execution criteria for the UE to perform relay selection (or reselection). Similarly, features of this disclosure provide techniques for conditionally switching back from a PC5 connection to a Uu connection when conditional handover execution criteria are met (e.g., the sidelink signal strength between two UEs drops below a channel condition threshold). Additionally, the techniques provided herein support conditional handover of a relay UE from a first base station to a second base station when the relay UE also supports one or more remote UEs.

[0007] In one example, a method, apparatus (device), and non-transient computer-readable medium for wireless communication are disclosed. The method may include receiving conditional handover configuration information from a source base station at a first user equipment (UE), wherein the conditional handover configuration information partially includes conditional handover execution criteria that should be met by the first UE to perform a conditional handover. The method may further include determining at the first UE that the conditional handover execution criteria are met, in part, based on either a channel condition between the first UE and the source base station falling below a channel condition threshold or a sidelink channel condition between the first UE and the second UE falling below a sidelink channel condition threshold. The method may further include triggering a conditional handover at the first UE to transfer communication from the source base station to the target base station via a direct communication path or a relay path.

[0008] In another example, a different method, apparatus (device), and non-transient computer-readable medium for wireless communication are disclosed. The method may include receiving a measurement report from a first user equipment (UE) at a source base station, wherein the measurement report indicates signal quality between the first UE and the source base station. The method may further include identifying one or more candidate target base stations for the first UE to switch communication from the source base station to, wherein the one or more candidate target base stations are intended for the first UE to be located within the coverage area of ​​the one or more candidate target base stations. The method may further include generating conditional handover configuration information for the first UE, partially based on the identification of the one or more candidate target base stations, wherein the conditional handover configuration information partially includes conditional handover execution criteria that the first UE should meet to perform a conditional handover. The method may further include transmitting the conditional handover configuration information to the first UE.

[0009] To achieve the foregoing and related objectives, these one or more aspects include the features fully described below and specifically pointed out in the claims. Certain illustrative features of these one or more aspects are set forth in detail in the following description and drawings. However, these features merely indicate a few of the various ways in which the principles of these various aspects may be employed, and this description is intended to cover all such aspects and their equivalents. Brief description of the attached diagram

[0011] The disclosed aspects will now be described in conjunction with the accompanying drawings, which are provided for illustrative purposes and not for limiting the scope of the disclosure, wherein similar reference numerals denote similar elements, and wherein:

[0012] Figure 1 These are schematic diagrams illustrating examples of wireless communication systems according to various aspects of this disclosure;

[0013] Figure 2 This is a schematic diagram illustrating an example of relay communication between a remote UE and a base station via a relay UE according to various aspects of this disclosure;

[0014] Figure 3 This is a diagram illustrating an example of wireless relay communication between a relay UE, a remote UE, and a base station according to various aspects of this disclosure;

[0015] Figure 4 This is a diagram illustrating an example of a remote UE that can switch communication from a direct base station to relay communication via a relay UE, according to various aspects of this disclosure;

[0016] Figure 5A This is a flowchart illustrating an example communication flow for conditional switching between the preparation Uu surface and PC5 (and vice versa) according to various aspects of this disclosure;

[0017] Figure 5B This is a flowchart illustrating an example communication flow for conditional switching between the trigger Uu surface and PC5 (and vice versa) according to various aspects of this disclosure;

[0018] Figure 6 This is a flowchart illustrating an example communication flow that triggers conditional handover of relay UE mobility according to various aspects of this disclosure;

[0019] Figure 7 These are schematic diagrams illustrating example implementations of various components of user equipment based on various aspects of this disclosure;

[0020] Figure 8 This is a flowchart illustrating an example of a wireless communication method implemented by a UE according to various aspects of this disclosure;

[0021] Figure 9 These are schematic diagrams illustrating example implementations of various components of a base station according to various aspects of this disclosure; and

[0022] Figure 10 This is a flowchart illustrating an example of a wireless communication method implemented by a base station according to various aspects of this disclosure.

[0023] An appendix is ​​included, including additional figures and descriptions.

[0024] Detailed description

[0025] In recent years, with the launch of numerous smart handheld devices, user demand for mobile broadband has increased. For example, the growth of bandwidth-intensive applications such as video streaming and multimedia file sharing is putting immense pressure on the limits of current cellular systems. Current cellular systems generally rely on base stations to support wireless communication for multiple user equipment (UEs) within a specific coverage area. Therefore, each base station can provide communication coverage for its respective geographical area, and overlapping geographical coverage areas are possible. Thus, when a UE is within the coverage area of ​​a base station, it can maintain direct communication with that base station via a Uu path or connection. However, UEs typically move back and forth between the coverage areas of one base station and another. Therefore, when a UE moves from the coverage area of ​​one base station to the coverage area of ​​another, the UE and / or the base station can initiate a handover procedure to enable seamless connectivity for the UE.

[0026] However, in some scenarios, the UE also moves out of the base station's coverage area into areas not covered by any base station. One solution to this problem relies on functionality for direct UE-UE communication (also known as device-to-device (D2D) or sidelink communication), which allows two nearby devices (e.g., UEs) to communicate with each other within the cellular bandwidth without involving a base station or with a limited number of base stations. Thus, a UE outside the coverage area of ​​any base station (e.g., a remote UE) can access the network via a relay UE within the coverage area of ​​that base station. In other words, the relay UE can act as an intermediary between the base station and the remote UE. The relay UE and the remote UE can communicate via sidelink communication (referred to as a PC5 connection). Even so, this method presents technical challenges in current systems. Specifically, conventional systems do not provide a mechanism for UEs (e.g., remote UEs or relay UEs) to easily switch between Uu connections (e.g., direct connections between the UE and the base station) and PC5 connections (e.g., sidelink communication between the remote UE and the relay UE).

[0027] This disclosure provides techniques for configuring and triggering conditional handover for UE mobility between direct connections (Uu connections) and / or relay connections (PC5 connections) to a base station. Specifically, conditional handover configuration may include multiple candidate relay UEs prepared for handover (e.g., from a Uu connection to a PC5 connection) and conditional handover execution criteria for the UE to perform relay selection (or reselection). Similarly, features of this disclosure provide techniques for conditionally switching back from a PC5 connection to a Uu connection when conditional handover execution criteria are met (e.g., the sidelink signal strength between two UEs drops below a channel condition threshold). Additionally, the techniques provided herein support conditional handover of a relay UE from a first base station to a second base station when the relay UE also supports one or more remote UEs.

[0028] Now refer to Figure 1-10 The various aspects are described in more detail below. Numerous specific details are set forth for illustrative purposes to provide a thorough understanding of one or more aspects. However, it is obvious that such aspects can be practiced without these specific details. Furthermore, as used herein, the term "component" can refer to one of the parts that make up a system, can be hardware, firmware, and / or software stored on a computer-readable medium, and can be divided into other components.

[0029] The following description provides examples and is not intended to limit the scope, applicability, or examples set forth in the claims. Changes may be made to the function and arrangement of the elements discussed without departing from the scope of this disclosure. Various procedures or components may be appropriately omitted, substituted, or added to the examples. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Furthermore, features described with reference to some examples may be combined in other examples.

[0030] Figure 1 This is a diagram illustrating an example of a wireless communication system and access network 100. The wireless communication system (also known as a wireless wide area network (WWAN)) may include base station 102, UE 104, evolved packet core (EPC) 160, and / or 5G core (5GC) 190. Base station 102 may include macrocells (high-power cellular base stations) and / or small cells (low-power cellular base stations). Macrocells may include base stations. Small cells may include femtocells, picocells, and microcells. In one example, base station 102 may also include gNB 180, as further described herein.

[0031] In some examples, one or more UEs can connect directly to a base station via a Uu connection or via a PC5 connection through a relay UE. Specifically, the first connection between a UE (hereinafter referred to as a "remote UE") and an infrastructure node (e.g., a gNB) of a network entity may be referred to as a Uu connection or via a Uu path. A remote UE in a Uu connection can use, for example, a conventional cellular mode to access network resources via a base station. For example, a remote UE can communicate with a network entity via a serving base station using a Uu connection through a conventional cellular link.

[0032] A second connection between a remote UE and another UE (hereinafter referred to as a "relay UE") may be referred to as a PC5 connection or via a PC5 path. A PC5 connection is a D2D connection that can utilize the comparative proximity between the remote UE and the relay UE (e.g., when the remote UE is closer to the relay UE than the nearest base station). The relay UE may also connect to an infrastructure node (e.g., a gNB) via a Uu connection and relay that Uu connection to the remote UE via a PC5 connection. This disclosure provides various examples to illustrate when and how a remote UE is switched from one connection (Uu connection or PC5 connection) to another to enable the remote UE to have the most efficient and / or most effective connection with the network or the relay UE.

[0033] In the absence of a PC5 connection, a remote UE can connect to a relay UE via a shared network with which both the remote UE and the relay UE communicate. However, when the remote UE can communicate efficiently with the relay UE via a sidelink (e.g., V2X), the remote UE can use the sidelink without the network to gain capacity, increase throughput, have less latency, and / or improve reliability. In other cases, the remote UE may prefer to connect to the network via the relay UE when this indirect connection can improve communication performance. In this disclosure, the change between a Uu connection (i.e., a direct connection to the network) and a PC5 connection (i.e., a direct connection to another UE or relay UE) may be referred to as relay mobility, handover, or transition. Aspects of this disclosure relate to (1) when such relay mobility should be triggered; (2) how each of the remote UE, relay UE, and network should operate during the handover procedure at the time of triggering; and (3) how each of the remote UE, relay UE, and network should operate upon completion.

[0034] In some respects, UE 104 (e.g., a remote UE) and UE 106 (e.g., a relay UE) may include a conditional handover configuration component 750 configured to handle data transmissions (such as relaying data transmissions during a handover procedure) during the handover process (see [link to relevant documentation]). Figure 7 The conditional handover configuration component 750 may also trigger a handover process based on determining that one or more conditional handover criteria are met. In some aspects, the base station may include a handover component 950 configured to configure and initiate a conditional handover procedure to move UE 104 and UE 106 to another base station (or vice versa) (see [link to handover configuration component 950]). Figure 9 For example, the handover component 950 may receive one or more measurement reports from UE104 and / or UE106, and may determine, at least in part, whether to configure the UE for a conditional handover procedure, including conditional handover execution criteria, based on one or more of these measurement reports. The handover component 950 may also prepare one or more relay UEs in response to the conditional handover configuration.

[0035] Base station 102 configured for 4G LTE (which may be collectively referred to as Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN)) can interface with EPC 160 via backhaul link 132 (e.g., using the S1 interface). Base station 102 configured for 5G NR (which may be collectively referred to as Next Generation RAN (NG-RAN)) can interface with 5GC 190 via backhaul link 184. Among other functions, base station 102 may also perform one or more of the following functions: user data delivery, radio channel cryptography and cryptography decoding, integrity protection, header compression, mobility control functions (e.g., handover, dual connectivity), inter-cell interference coordination, connection establishment and release, load balancing, distribution of Non-Access Stratum (NAS) messages, NAS node selection, synchronization, Radio Access Network (RAN) sharing, Multimedia Broadcast Multicast Service (MBMS), subscriber and equipment tracking, RAN Information Management (RIM), paging, location, and delivery of alarm messages. Base stations 102 can communicate directly or indirectly (e.g., via EPC 160 or 5GC 190) on backhaul link 134 (e.g., using an X2 interface). Backhaul link 134 can be wired or wireless.

[0036] Base station 102 can wirelessly communicate with one or more UEs 104. Each base station 102 can provide communication coverage for its respective geographical coverage area 110. Overlapping geographical coverage areas 110 may exist. For example, a small cell 102' may have a coverage area 110' that overlaps with the coverage areas 110 of one or more macro base stations 102. A network that includes both small cells and macro cells may be referred to as a heterogeneous network. The heterogeneous network may also include a Home Evolved B Node (eNB) (HeNB), which can provide services to a restricted group (which may be referred to as a Closed Subscriber Group (CSG)). The communication link 120 between base station 102 and UE 104 may include uplink (UL) (also known as reverse link) transmission from UE 104 to base station 102 and / or downlink (DL) (also known as forward link) transmission from base station 102 to UE 104. The communication link 120 may use multiple-input multiple-output (MIMO) antenna technologies, including spatial multiplexing, beamforming, and / or transmit diversity. These communication links may use one or more carriers. For each carrier allocated in a total of up to Yx MHz (e.g., for x component carriers) used for transmission in the DL and / or UL directions, base station 102 / UE 104 may use a spectrum with a bandwidth of up to Y MHz (e.g., 5, 10, 15, 20, 100, 400 MHz, etc.). These carriers may or may not be adjacent to each other. Carrier allocation may be asymmetric with respect to DL and UL (e.g., more or fewer carriers may be allocated to DL compared to UL). Component carriers may include primary component carriers and one or more secondary component carriers. The primary component carrier may be referred to as the primary cell (PCell), and the secondary component carriers may be referred to as secondary cells (SCells).

[0037] In another example, some UEs 104 may communicate with each other using a device-to-device (D2D) communication link 158. The D2D communication link 158 may use DL / UL WWAN spectrum. The D2D communication link 158 may use one or more sidelink channels, such as the Physical Sidelink Broadcast Channel (PSBCH), Physical Sidelink Discovery Channel (PSDCH), Physical Sidelink Shared Channel (PSSCH), and Physical Sidelink Control Channel (PSCCH). D2D communication can be achieved through a wide variety of wireless D2D communication systems, such as, for example, FlashLinQ, WiMedia, Bluetooth, ZigBee, Wi-Fi based on the IEEE 802.11 standard, LTE, or NR.

[0038] The wireless communication system may further include a Wi-Fi access point (AP) 150 communicating with a Wi-Fi station (STA) 152 via a communication link 154 in the 5 GHz unlicensed spectrum. When communicating in the unlicensed spectrum, the STA 152 / AP 150 may perform a clear channel assessment (CCA) before communication to determine whether the channel is available.

[0039] Small cell 102' can operate in licensed and / or unlicensed spectrum. When operating in unlicensed spectrum, small cell 102' can employ NR and use the same 5 GHz unlicensed spectrum as that used by Wi-Fi AP 150. Small cell 102' employing NR in unlicensed spectrum can enhance access network coverage and / or increase access network capacity.

[0040] Whether it's a small cell 102' or a large cell (e.g., a macro base station), base station 102 can include an eNB, a gB node (gNB), or other types of base stations. Some base stations (such as gNB 180) can operate one or more frequency bands within the electromagnetic spectrum. The electromagnetic spectrum is typically subdivided into various classes, bands, channels, etc., based on frequency / wavelength. In 5G NR, two initial operating frequency bands have been identified as frequency range designations FR1 (410MHz–7.125GHz) and FR2 (24.25GHz–52.6GHz). The frequencies between FR1 and FR2 are generally referred to as mid-band frequencies. Although a portion of FR1 is greater than 6GHz, in various documents and articles, FR1 is often (interchangeably) referred to as the "sub-6GHz band." Similar naming issues sometimes arise with FR2. Although it is different from the Very High Frequency (EHF) band (30 GHz–300 GHz) which is identified by the International Telecommunication Union (ITU) as the “millimeter wave” (mmW) band, FR2 is generally (interchangeably) referred to as the “millimeter wave” band in various documents and articles.

[0041] Considering the above aspects, unless otherwise stated, it should be understood that, as used herein, the term "sub-6GHz" and the like can broadly refer to frequencies less than 6GHz, within FR1, or including intermediate frequency band frequencies. Furthermore, unless otherwise stated, it should be understood that, as used herein, the term "millimeter wave" and the like can broadly refer to frequencies including intermediate frequency band frequencies, within FR2, or within the EHF band. However, communication using the mmW radio frequency band has extremely high path loss and short range. The mmW base station 180 can utilize beamforming 182 with the UE 110 to compensate for the high path loss and short range.

[0042] EPC 160 may include Mobility Management Entity (MME) 162, other MMEs 164, Serving Gateway 166, Multimedia Broadcast Multicast Service (MBMS) Gateway 168, Broadcast Multicast Service Center (BM-SC) 170, and Packet Data Network (PDN) Gateway 172. MME 162 may communicate with Home Subscriber Server (HSS) 174. MME 162 is the control node that handles signaling between UE 104 and EPC 160. Generally, MME 162 provides bearer and connection management. All user Internet Protocol (IP) packets are delivered through Serving Gateway 166, which is itself connected to PDN Gateway 172. PDN Gateway 172 provides UE IP address allocation and other functions. PDN Gateway 172 and BM-SC 170 are connected to IP Service 176. IP Service 176 may include the Internet, intranet, IP Multimedia Subsystem (IMS), PS streaming service, and / or other IP services. The BM-SC 170 provides functionality for MBMS user service provisioning and delivery. The BM-SC 170 can serve as an entry point for content provider MBMS transmissions, authorize and initiate MBMS bearer services within a Public Land Mobile Network (PLMN), and schedule MBMS transmissions. The MBMS gateway 168 can be used to distribute MBMS traffic to base station 102 within a Broadcast-Specific Service Single Frequency Network (MBSFN) area, and can be responsible for session management (start / stop) and collecting eMBMS-related billing information.

[0043] 5GC 190 may include Access and Mobility Management Functions (AMF) 192, other AMFs 193, Session Management Functions (SMF) 194, and User Plane Functions (UPF) 195. AMF 192 may communicate with Unified Data Management (UDM) 196. AMF 192 may be a control node handling signaling between UE 104 and 5GC 190. Generally, AMF 192 provides QoS streaming and session management. User Internet Protocol (IP) packets (e.g., from one or more UEs 104) may be transmitted via UPF 195. UPF 195 provides UE IP address allocation for one or more UEs, as well as other functions. UPF 195 connects to IP service 197. IP service 197 may include the Internet, intranet, IP Multimedia Subsystem (IMS), PS streaming service, and / or other IP services.

[0044] The base station may also be referred to as a gNB, B-node, evolved B-node (eNB), access point, base transceiver station, radio base station, radio transceiver, transceiver function, basic service set (BSS), extended service set (ESS), transmit / receive point (TRP), or any other suitable term. Base station 102 provides UE 104 with access to EPC 160 or 5GC 190. Examples of UE 104 include cellular phones, smartphones, Session Initiation Protocol (SIP) phones, laptop devices, personal digital assistants (PDAs), satellite radios, GPS devices, multimedia devices, video devices, digital audio players (e.g., MP3 players), cameras, game consoles, tablet devices, smart devices, wearable devices, vehicles, electricity meters, gas pumps, large or small kitchen appliances, healthcare devices, implants, sensors / actuators, displays, or any other similar functional devices. Some UE 104 devices may be referred to as IoT devices (e.g., parking timers, oil pumps, ovens, vehicles, heart monitors, etc.). IoT UEs may include Machine Type Communication (MTC) / Enhanced MTC (eMTC, also known as Category (CAT)-M, Cat M1) UEs, NB-IoT (also known as CAT NB1) UEs, and other types of UEs. In this disclosure, eMTC and NB-IoT may refer to technologies that may evolve from or be based on these technologies. For example, eMTC may include FeMTC (Further eMTC), eFeMTC (Further Enhanced eMTC), mMTC (Massively Multi-Level MTC), etc., while NB-IoT may include eNB-IoT (Enhanced NB-IoT), FeNB-IoT (Further Enhanced NB-IoT), etc. UE 104 may also be referred to as a station, mobile station, subscriber station, mobile unit, subscriber unit, radio unit, remote unit, mobile device, radio device, wireless communication device, remote device, mobile subscriber station, access terminal, mobile terminal, radio terminal, remote terminal, handheld device, user agent, mobile client, client, or some other suitable term.

[0045] Figure 2 This is a schematic diagram 200 illustrating an example of relaying communication between a remote UE 106 and a base station 102 via a relay UE 104. It should be understood that in some examples, the hardware capabilities of both the relay UE 104 and the remote UE 106 may be identical.

[0046] Base station 102 provides communication coverage to geographical coverage area 210. As shown, relay UE 104 can be within the coverage area 210 of base station 102. However, in this scenario, remote UE 106 can be outside the coverage area 210 of base station 102. Therefore, remote UE 106 can request relay service from relay UE 104 when remote UE 106 is unable to establish a direct connection with base station 102 and / or the direct connection with base station 102 is degraded (e.g., remote UE 106 moves out of the coverage area 210 of base station 102). For example, there may be atmospheric and environmental interference between remote UE 106 and base station 102, where remote UE 106 may need to transmit or receive data through relay UE 104.

[0047] A relay UE (e.g., 104) can monitor relay requests from other UEs (e.g., 106). For example, relay UE 104 can be configured to listen for / attempt to detect relay requests from nearby UEs during monitoring periods. In some examples, to enable identification, relay UE 104 can periodically announce its presence by transmitting sidelink discovery messages, and / or remote UE 106 can periodically announce sidelink relay request messages. Messages indicating a request to relay to base station 102 can be referred to as relay requests, relay requests, or other names. Sidelink discovery messages can indicate the capabilities of relay UE 104 acting as a relay and / or indicate the sidelink communication capabilities of relay UE 104. During this process, remote UE 106 can obtain the UE identifier (ID) of relay UE 104 for sidelink transmission and / or reception of relayed traffic. In some examples, an indication of the presence of relay UE 104 as a potential relay may be sent after remote UE 106 requests relaying. Relay UE 104 may indicate its availability to operate as a relay between remote UE 106 and base station 102 in response to receiving the request from the remote UE. This message may be a broadcast indication broadcast on the sidelink or a unicast message transmitted to the remote UE on the sidelink.

[0048] After transmitting a discovery message or receiving a relay request, communication (e.g., a PC5 connection) can be established between relay UE 104 and remote UE 106. Remote UE 106 can also communicate with relay UE 104 to perform mutual authentication (e.g., direct security mode) procedures. In some examples, the PC5 signaling protocol can be used for direct connection management functions such as direct link establishment / release, security parameter control, and IP address allocation. In some examples, remote UE 106 and relay UE 104 can negotiate the communication relay between the remote UE and the base station.

[0049] After remote UE 106 and relay UE 104 have discovered each other, remote UE 106 can be configured to send a message informing base station 102 of the potential relay UE 104. This message may indicate the presence and / or availability of relay UE 104. Remote UE 106 may send one or more measurement reports informing of the detected relay UE and / or a sidelink measurement report for relay UE 106 to base station 102. The sidelink measurement report may correspond to the measured channel quality (e.g., sidelink reference signal received power (RSRP)) between remote UE 106 and relay UE 104. The sidelink measurement report may also include an explicit or implicit relay UE identifier. Based on this message and / or the sidelink measurement report, base station 102 may perform relay UE selection to determine whether relay UE 104 has met the thresholds for becoming relay UE 104 and / or whether relay UE 104 is a suitable or optimal relay candidate when multiple candidates (e.g., multiple relay UEs) may exist. Base station 102 may determine whether the relay UE 104 is eligible to provide relay services and / or select the relay UE 104 to provide relay services based on measured channel quality (e.g., RSRP measurement).

[0050] Figure 3Figure 300 illustrates an example of wireless relay communication between relay UE 104 and remote UEs (e.g., first remote UE 106-a and second remote UE 106-b) and base stations 102-a and 102-b. The first remote UE 106-a and the second remote UE 106-b can be connected to relay UE 104, such as via a PC5 connection or a sidelink. Relay UE 104 can further be communicatively coupled to one of a plurality of base stations (e.g., base station 102-a or 102-b) via a Uu interface. Base stations 102-a and 102-b can further be communicatively coupled to core network 190 (e.g., a 5G core network) via an N2 interface. The term "radio access" can be used to refer to the Uu interface. Base stations (e.g., 102-a and 102-b) can also communicate with each other using an Xn interface. Thus, the first remote UE 102-a and the second remote UE 102-b can access the core network 190 via the relay UE 104. For example, the first remote UE 106-a can send data to the core network 190 by first transmitting the data to the relay UE 104 via the PC5 interface, and the relay UE 104 can forward the data to the base station 102 (e.g., the first base station 102-a or the second base station 102-b) via the Uu interface. The base station 102 then sends the data to the core network 190 via the N2 link. Similarly, the second remote UE 106-b can receive data from the core network 190, whereby the core network 190 can first forward the data to the relay UE 104 via base stations 102-a and / or 102-b, and the relay UE 104 then forwards the data to the second remote UE 106-b.

[0051] One or more types of architectures, implementations, and / or designs may exist for the relay UE (e.g., 104), such as Layer 2 (L2) relay and / or Layer 3 (L3) relay. For L3 relay, remote UE 106 may be communicatively coupled to relay UE 104 via a PC5 interface, where the control plane in the PC5 interface may include one or more of the Radio Resource Control (RRC) layer, Packet Data Convergence Protocol (PDCP) layer, Radio Link Control (RLC) layer, Media Access Control (MAC) layer, and physical layer. The PC5 unicast link may be configured for relay UE 104 to serve remote UEs 106-a and 106-b. In some examples, remote UE 106 may not have a Uu Access Layer (AS) connection to the Radio Access Network (RAN) on the relay path and may not have a direct Non-Access Layer (NAS) connection to the core network (e.g., 5G core network). Therefore, remote UE 106-a may not be visible to the core network 190. However, remote UE 106 can report its presence to core network 190 via a relay (e.g., via relay UE 104). Remote UE 106 can also make itself known to the core network via non-3GPP networking (N3IWF).

[0052] In an L2 UE-to-NW relay, the remote UE 106 may include a PC5 control plane (e.g., an interface) and a Uu control plane. The PC5 control plane can be used to configure the PC5 unicast link between the remote UE 106 and the relay UE 104 prior to relaying. The remote UE 106 may support Uu AS and Non-Access Stratum (NAS) connections (e.g., above PC5 RLC), where the RAN can control the PC5 link of the remote UE via RRC. For example, NAS and AS messages (such as RRC signaling messages or messages generated by the remote UE 106) may be sent to the PC5 layer and pass through the relay UE 104. The control plane protocol stack may include an adaptation layer to support the multiplexing of traffic from multiple UEs on the Uu link of the relay UE. For example, the adaptation layer of the relay UE 104 may handle and identify data packets to be sent or relayed to the base station 102.

[0053] In some scenarios, one or both of relay unit 104 and / or remote UE 106 may be moved out of the coverage area of ​​one or more base stations 102. For example, as Figure 3 As explained, relay UE 104 can move from the coverage area of ​​the first base station 102-a (or "source base station") to the coverage area of ​​the second base station 102-b. However, during this transition, relay UE 104 can support relay communication for one or more remote UEs 106.

[0054] Relay UE 104 can trigger a mobility handover from first base station 102-a to second base station 102-b based on one or more channel measurements. For example, mobility triggering can utilize downlink (DL) measurements of relay UE 104. For instance, relay UE 104 can provide intra-frequency, inter-frequency, and RAT-inter-frequency measurements to the network to determine whether criteria for handover from first base station 102-a to second base station 102-b are met. In some cases, network 190 can determine when to initiate a handover based on DL measurements. In other cases, relay UE 104 can use DL measurements to determine and initiate the handover. Upon taking the action to initiate the handover, a target link (Uu connection) with second base station 102-b can be established.

[0055] As shown in the following reference Figure 5A , 5B As discussed in more detail in section 6, the UE can be configured to conditionally hand over between a direct connection (Uu connection) and / or a relay connection (PC5 connection) to a base station for UE mobility. Specifically, the conditional handover configuration may include multiple candidate relay UEs prepared for handover (e.g., from Uu connection to PC5 connection) and conditional handover execution criteria for the UE to perform relay selection (or reselection). Similarly, features of this disclosure provide techniques for conditionally handing over from PC5 connection back to Uu connection when conditional handover execution criteria are met (e.g., the sidelink signal strength between the two UEs drops below a channel condition threshold). Additionally, the techniques provided herein support conditional handover of a relay UE from a first base station to a second base station when the relay UE also supports one or more remote UEs.

[0056] Similarly, in some scenarios, such as in Figure 4 In this scenario, remote UE 106 can switch communication from direct base station 102-a to relay communication via relay UE 104. Mobility triggering can utilize DL measurements from remote UE 106. For example, remote UE 106 can provide intra-frequency, inter-frequency, and RAT-inter-frequency measurements to network 190 to determine whether handover criteria are met. In some cases, network 190 can determine when to initiate a handover based on DL measurements. In other cases, remote UE 106 can use DL measurements to determine and initiate the handover.

[0057] When initiating the handover, a target link (PC5 connection or Uu connection) may be established. Target link establishment may include a context transfer prior to the remote UE 106 handover to the target link. For example, the handover may include target link establishment based on the context of the remote UE's existing connection and the configuration of dedicated / shared UE resources. Upon completion, the handover may include forwarding data from the source connection to the target connection. In some cases, user plane handover may be included. In other cases, resources may be released at the source cell.

[0058] Figure 5A The explanation is for the reference. Figure 4 The flowchart 500 illustrates an example communication flow for conditional handover between the Uu plane and the PC5 plane (and vice versa) in the described scenario. Initially, the UE 104 can communicatively couple with the source base station 102-a via the Uu path and access the core network 190.

[0059] At 505, on one hand, source base station 102-a may receive one or more measurement reports from UE 104. These measurement reports may, for example, signal to inform UE 104 of potentially deteriorating channel condition measurements between source base station 102-a. Based at least in part on the one or more measurement reports received from UE 104, source base station 102-a may determine to configure a conditional handover procedure, such as moving UE 104 to target base station 102-b, if the signal quality continues to deteriorate below a channel condition threshold.

[0060] If source base station 102-a determines to initiate a conditional handover based on the measurement report, source base station 102-b may configure one or both of the following for UE 104: intra-gNB or inter-gNB handover preparation (collectively, "conditional handover preparation"). Specifically, the handover may be inter-base station (e.g., inter-gNB) or intra-base station (e.g., intra-gNB) handover. Source base station 102-a may communicate with target base stations 102-b and 102-c via the Xn network interface.

[0061] Conditional handover preparation may include identifying and configuring source base station 102-a and / or candidate target base stations (e.g., first target gNB 102-b and / or second target gNB 102-c). In some aspects, conditional handover preparation may prepare a conditional handover configuration for UE 104. This preparation may include identifying criteria for selecting one or more relay UEs 104. For example, the criteria may include determining whether UE 104 meets the Sidelink Discovery Reference Signal Power (SD-RSRP) for transitioning from a Uu connection to a PC5 connection (e.g., from a direct base station connection to a relay connection) and / or the Sidelink Reference Signal Received Power (SL-RSRP) for moving UE 104 from a PC5 connection to a Uu connection (e.g., from a relay connection via a relay UE to a direct base station connection). For the purposes of this disclosure, SD-RSRP and / or SL-RSRP may be collectively referred to as “sidelink channel conditions”.

[0062] Specifically, one or both of the source base station 102-a and / or candidate target base stations 102-b, 102-c may be prepared for one or more relay UEs 104 to connect to via a PC5 connection providing access to one or more base stations 102 (see [link to relevant documentation]). Figure 2-4 One or more relay UEs 104 may be within the coverage area of ​​one or more of the source base station 102-a and / or the target base stations 102-b and 102-c, and may communicate with base station 102 via a Uu connection. Thus, as described above, in the preparation of one or more relay UEs 104 as part of a conditional handover procedure, base station 102 may provide conditional handover configuration information, which may include criteria for UE 104 to perform conditional handover between Uu to PC5 handover (e.g., from source base station 102-a to one or more relay UEs 104) and PC5 back to Uu handover (e.g., from one or more relay UEs 104 back to a base station (including source base station 102-a or target base stations 102-b and 102-c)).

[0063] At 520, source base station 102-a may send an RRC reconfiguration message to UE 104. The RRC reconfiguration message may include conditional handover configuration information for both intra-gNB and / or inter-gNB handovers. The conditional handover configuration information may indicate to UE 104 specific criteria upon which UE 104 may perform a conditional handover, as well as criteria for selecting one or more relay UEs 104. Thus, at 525, UE 104 may verify the conditional handover configuration information, including determining whether the channel conditions (e.g., signal strength) between UE 104 and the source base station via the Uu connection have fallen below a channel condition threshold. If the channel condition drops below the channel condition threshold, UE 104 may identify one or more relay UEs 104 configured by source base station 102-a (e.g., UE 104 connected to source base station 102-a by intra-gNB handover) and one of a plurality of candidate target base stations 102-b, 102-c (UEs connected to one or both of candidate target base stations 102-b, 102-c by inter-gNB handover).

[0064] Therefore, in some aspects, UE 104 can select the relay UE 104 to switch to the PC5 connection based on the conditional handover configuration information verified in 525. In 530, as part of the conditional handover configuration, source base station 102-a can forward pending data to one or both of candidate target base stations 102-b and 102-c. However, when UE 104 performs a handover to candidate target base station 102 via a relay UE 104 associated with candidate target base station 102, UE 104 can maintain its Uu connection with source base station 102-a to minimize communication interruptions. Therefore, in 535, user data can be transmitted between UE 104 and core network 190 via source base station 102-a. In 540, UE 104 can transmit an RRC reconfiguration complete message to source base station 102-a.

[0065] Figure 5B The explanation is for the reference. Figure 4 The flowchart 550 describes an example communication flow for conditional switching between the triggering Uu face and the PC5 face (and vice versa) in the described scenario. In some respects, flowchart 550 may follow sequentially in reference to... Figure 5A Following the steps described in flowchart 500.

[0066] In 555, the remote UE 106 can trigger a conditional handover when it is determined that the conditional handover triggering criteria are met. In some aspects, the conditional handover triggering criteria can be pre-configured or derived from the source base station 102-a (see [link to relevant documentation]). Figure 5AUpon determining that the conditional handover triggering criteria are met, the remote UE 104 may verify the target base station configuration (including identifying one or more candidate relay UEs 104) and verify the availability of the target path configuration (e.g., PC5 or Uu path) to one or more target base stations 102-b, 102-c. Furthermore, when the remote UE 106 performs the conditional handover procedure, the remote UE 106 may maintain its connection with the source base station 102-a until the target path is established. Therefore, the remote UE 104 and the source base station 102-a may continue to exchange data until the remote UE 104 completes the handover from Uu to PC5 (or from PC5 to Uu).

[0067] At 560, the remote UE 106 may establish a target access path (e.g., PC5 or Uu path) to target base stations 102-b and 102-c via candidate relay UE 104 (PC5 connection). In some examples, the access path may include selecting relay UE 104 from a plurality of candidate relay UEs configured by one or more of the source base station 102-a, the first target base station 102-b, and / or the second target base station 102-c. In some examples, the selected relay UE 104 may be within the coverage area of ​​the first target base station 102-b and thus communicate with the first target base station 102 via the Uu path. Relay UE 104 may be selected by the remote UE 106 from the plurality of candidate relay UEs based on the sidelink channel condition criteria discussed above (e.g., SD-RSRP and / or SL-RSRP).

[0068] At 565, after the target access path has been established between the remote UE 106, the relay UE 104, and the first target base station 102-b, the remote UE 106 can transmit an RRC reconfiguration complete message to the first target base station 102-b. At 570, the first target base station 102-b can transmit a handover success message to the source base station 102-a.

[0069] At 575, source base station 102-a may forward all pending data associated with remote UE 106 to first target base station 102-b. At 580, first target base station 102-b may release the remote UE context for any configured candidate relay UEs not selected by remote UE 106. In other words, once remote UE 106 selects relay UE 104 from a plurality of candidate relay UEs for PC5 communication based on one or more configured criteria (e.g., SD-RSRP and / or SL-RSRP), target base stations 102-b and 102-c may release the remote UE 106 context for all remaining candidate relay UEs.

[0070] Similarly, at 585, source base station 102-a can transmit a message (e.g., a handover cancellation message) to second target base station 102-c, indicating that remote UE 106 has initiated a conditional handover connection with first target base station 102-b. In other examples, source base station 102-a can transmit a message (e.g., a handover cancellation message) indicating that the handover of remote UE 106 no longer requires second target base station 102-c. Thus, at 590, second target base station 102-c can also release the context of remote UE 106 from the configured candidate relay UE established by second target base station 102-c. At 595, source base station 102-a can also release the remote UE context, and at 598, the source connection between remote UE 106 and source base station 102-a is released after the handover to first target base station 102-b (via relay UE 104).

[0071] Although Figure 5A and 5B The Uu-to-PC5 mobility of UE 104 has been explained, but it should be understood that the same procedure can also be applied to PC5-to-Uu mobility. In fact, the RRC reconfiguration message 520 may include, for example, conditional handover configuration information that also informs UE 104 of the conditions under which UE 104 can handover back to one of base stations 102 via a Uu connection. One such criterion may include the following conditions: the sidelink channel condition (e.g., SL-RSRP) on the PC5 connection between UE 104 and relay UE 104 falls below the sidelink connection threshold, while the RSRP between UE 104 and base stations 102 (source base station 102-a and / or candidate target base stations 102-b, 102-c) exceeds the channel condition threshold. In this scenario, the conditional handover condition may specify a handover from relying on relay UE 104 to a direct connection to base station 102 via a Uu connection.

[0072] Figure 6 The explanation is for the reference. Figure 3 A flowchart 600 illustrates an example communication flow for triggering conditional handover of relay UE mobility in the described scenario. In this example, relay UE 104 can move from the coverage area of ​​a first base station 102-a to the coverage area of ​​a second base station 102-b. Relay UE 104 can also provide relay connectivity (PC5 connectivity) to one or more remote UEs (e.g., a first remote UE 106-a and a second remote UE 106-b). In some aspects, remote UE 106 can maintain its PC5 connectivity with relay UE 104 during the handover process, or remote UE 106 can trigger a handover to another relay UE or redirect a Uu path to the target base station 102.

[0073] At 605, remote UE 106 can be communicatively coupled to relay UE 104, and relay UE 104 can in turn be communicatively coupled to source base station 102-a. Remote UE 106 can communicate with base station 102-a and can access core network 190 via relay UE 104. At 610, in one aspect, source base station 102-a can receive one or more measurement reports from relay UE 104 and / or remote UE 106 (e.g., via relay UE 104 at 605 or 610). Based at least in part on the measurement reports received from relay UE 104 and / or remote UE 106, source base station 102-a can decide whether to initiate a handover procedure, such as moving relay UE 104 and optionally remote UE 106 to target base station 102-b. In some aspects, source base station 102-a can configure conditional handover for relay UE 104 and / or remote UE 106.

[0074] On the other hand, the measurement report from relay UE 104 can indicate which (or which) remote UEs are likely candidates, such as Figure 3 106-a and / or 106-b) may move with relay UE 104 during handover. Additionally or alternatively, relay UE 104 may determine, at least in part, which remote UE(s) to carry during the handover of relay UE 105 based on sidelink measurement reports (e.g., channel conditions between the first and second UEs) between relay UE 104 and (the) remote UE(s). Thus, based on this indication, source base station 102-a may also determine which remote UE(s) may potentially be included in conditional handover preparation (e.g., group handover).

[0075] If the source base station 102-a determines at 615 that it needs to initiate a group handover, the source base station 102-a may configure one or more dedicated radio bearers (DRBs) of the remote UE 106 as dual active protocol stack (DAPS) DRBs, wherein the remote UE 106 can continue to use DAPS DRBs to transmit and / or receive data during the group handover, such as in combination with Figure 3Described. For example, since remote UE 106 may have its own Non-Access Stratum (NAS) and Uu Access Stratum (AS) connections to source base station 102-a, remote UE 106 may also have its own Packet Data Unit (PDU) sessions and DRB setups. Therefore, source base station 102-a may determine that one or more of the DRBs used for remote UE 106 may correspond to certain services that are more susceptible to interruption during handover, and may decide to configure these DRBs as DAPS DRBs. In particular, although the DAPS DRB configurations may be known to remote UE 106, relay UE 104 may not be aware of the DAPS DRB configurations.

[0076] Therefore, to support DAPS DRB configuration for remote UE 106 during relay UE handover (e.g., mobility), source base station 102-a can inform relay UE 104 which Uu Radio Link Control (RLC) channels of remote UE 106 can be disposed as DAPS Uu RLC channels. In one example, source base station 102-a can indicate the DAPS RLC channels of remote UE 106 to relay UE 104 during the initial configuration of Uu RLC channels for each remote UE. This provides source base station 102-a with dynamic control over the DAPS RLC channel configuration, which can be based at least in part on load and traffic conditions. For example, during handover, if the source channel does not have good channel conditions or is loaded or the target base station does not support DAPS configuration, the source channel may not be configured to support DAPS. In another example, source base station 102-a can indicate the DAPS RLC channels of remote UE 106 in the handover command for group handover sent to relay UE 104. For example, when the source base station 102-a is moving the relay UE 104 from the source base station 102-a to the target base station 102-b, the source base station 102-a can also indicate to the relay UE 104 any Uu RLC channels being handled by the remote UE 106 and which of them are DAPS RLC channels in the group handover handover command.

[0077] In 615, source base station 102-a enables target base station 102-b to prepare for a conditional handover operation between relay UE 104 and remote UE 106, which may also include DAPS DRB preparation. The handover may be an inter-base station (e.g., inter-gNB) handover or an intra-base station (e.g., intra-gNB) handover. Source base station 102-a may communicate with target base station 102-b via the Xn network interface. In one example, source base station 102-a may send a handover preparation message for relay UE 104 and each remote UE 106 to target base station 102-b. For example, see reference back. Figure 3If base station 102-a is preparing to move relay UE 104 and remote UEs 106-a and 106-b to target base station 102-b, source base station 102-a may send four preparation messages: one to target base station 102-b, one for relay UE 104, one for the first remote UE 106-a, and one for the second remote UE 106-b, etc. Source base station 102-a may also inform target base station 102-b in the preparation messages which DRBs will be disposed of as DAPS. Alternatively, source base station 102-a may send a handover preparation message to target base station 102-b, wherein the handover preparation message informs target base station 102-b to configure relay UE 104 and one or more remote UEs 106 for conditional handover. In some aspects, preparing for conditional handover of relay UE 104 may also include preparing a conditional handover cell for the mobility of remote UE 106.

[0078] After receiving the handover preparation message(s), the target base station 102-b can determine whether handover and / or handover configuration(s) are supported, and can send the confirmation message(s) to the source base station 102-a, such as confirming the handover request and / or the supported handover configuration(s) (e.g., DAPS DRB configuration). At 620, early or late data forwarding of traffic for both relay UE 104 and remote UE 106 can be supported at the source base station 102-a and / or the target base station 102-b using DAPS DRB.

[0079] In 625, source base station 102-a may send a conditional handover configuration command to relay UE 104 and / or remote UE 106, such as via an RRC reconfiguration message, to inform relay UE 104 and / or remote UE 106 of criteria(s) that may trigger a move from source base station 102-a to target base station 102-b. In some aspects, the conditional handover configuration information for relay UE 104 may further include conditional handover criteria for one or more remote UE handover command containers. Additionally, in addition to the conditional handover configuration, remote UE handover command containers may also be provided to relay UE 104.

[0080] At 630, relay UE 104 can verify the conditional handover execution criteria and begin monitoring the conditional handover cells prepared by the network. Furthermore, while relay UE 104 performs this verification, it can maintain its Uu connection with source base station 102-a to minimize communication interruptions. Therefore, at 635, user data can continue to be transmitted between UE 104, remote UE 106, and core network 190 via source base station 102-a. At 640, UE 104 can transmit an RRC reconfiguration complete message to source base station 102-a.

[0081] At 645, relay UE 104 can determine that the conditional handover execution criteria are met (e.g., the channel condition between relay UE 104 and source base station 102-a drops below a channel condition threshold). At 650, relay UE 104 can wait for the conditional handover execution criteria to be met before relaying a handover command to remote UE 106. In some aspects, relay UE 104 can relay handover commands to one or more remote UEs 106 at different times based on non-DAPS DRBs configured for one or more remote UEs 106.

[0082] By sending a handover command with a handover command container to the remote UE 106, the relay UE 104 may have more control over the handover procedure and may inform the remote UE 106 of the target base station 102-b. For example, since the relay UE 104 may have one or more Uu RLC channels, which may be DAPS RLC channels, for the remote UE 106, the remote UE may have already used the DAPS RLC channels to transmit and / or receive data with the source base station 102-a. At 655, after the relay UE 104 initiates a handover procedure based on the determination that the conditional handover criteria have been met, the remote UE 106 may continue to use its DAPS RLC channels to transmit data to the source base station 102-a while the relay UE 104 is performing an RRC connection with the target base station 102-b. However, after the relay UE 104 completes the RRC connection with the target base station 102-b, the relay UE 104 can inform the remote UE 106 of the target base station 102-b and connect the remote UE 106 to the target base station 102-b (e.g., by sending a handover command container to the remote UE).

[0083] Thus, in one example, relay UE 104 can transmit a handover command to one or more remote UEs 106 when it determines that the conditional handover execution criteria have been met and handover has begun. In other examples, the handover command can be sent upon successful handover to target base station 102-b. In either instance, remote UE 106 can then transmit and receive data from target base station 102-b after relay UE 104 has performed the handover to target base station 102-b. This method can be advantageous because it minimizes interruptions in data transmission for remote UE 106.

[0084] Figure 7 Hardware components and sub-components of an apparatus (which may be UE 104) for implementing one or more methods (e.g., method 800) described herein, according to various aspects of this disclosure, are explained. In some examples, UE 104 may be a reference... Figure 1-6The described relay UE 104 or remote UE 106. For example, an example implementation of UE 104 may include a wide variety of components, some of which have already been described above, but also include components such as one or more processors 712, memory 716, and transceiver 702 communicating via one or more buses 744, which may operate in conjunction with conditional switching configuration component 750 to perform the functions described herein in relation to one or more methods (e.g., 800) including this disclosure.

[0085] In some respects, the conditional handover configuration component 750 is configured to handle data transmission during the handover procedure, such as relaying data transmission during the handover procedure. The conditional handover configuration component 750 can also trigger the handover process based on determining that one or more conditional handover criteria are met.

[0086] One or more processors 712, modems 714, memory 716, transceivers 702, RF front-ends 788, and one or more antennas 765 may be configured to support voice and / or data calls (simultaneously or not simultaneously) in one or more radio access technologies. In one aspect, the one or more processors 712 may include modems 714 using one or more modem processors. Various functions associated with the conditional switching configuration component 750 may be included in modems 714 and / or processors 712, and in one aspect may be performed by a single processor, while in other aspects, different functions may be performed by a combination of two or more different processors. For example, in one aspect, the one or more processors 712 may include any one or any combination of: a modem processor, or a baseband processor, or a digital signal processor, or a transmitter processor, or a receiver processor, or a transceiver processor associated with transceiver 702. In other aspects, some features of the one or more processors 712 and / or modems 714 associated with the conditional switching configuration component 750 may be performed by transceiver 702.

[0087] Memory 716 may be configured to store data used herein and / or a local version of application 775, or one or more of conditional switching configuration components 750 and / or their sub-components executed by at least one processor 712. Memory 716 may include any type of computer-readable medium that can be used by a computer or at least one processor 712, such as random access memory (RAM), read-only memory (ROM), tape, magnetic disk, optical disk, volatile memory, non-volatile memory, and any combination thereof. In one aspect, for example, when UE 104 is operating at least one processor 712 to execute conditional switching configuration components 750 and / or one or more of their sub-components, memory 716 may be a non-transient computer-readable storage medium storing one or more computer-executable codes defining conditional switching configuration components 750 and / or one or more of their sub-components and / or associated data.

[0088] Transceiver 702 may include at least one receiver 706 and at least one transmitter 708. Receiver 706 may include hardware, firmware, and / or processor-executable software code for receiving data, the code comprising instructions and stored in memory (e.g., a computer-readable medium). Receiver 706 may be, for example, a radio frequency (RF) receiver. In one aspect, receiver 706 may receive signals transmitted by at least one UE 104. Additionally, receiver 706 may process such received signals and may also obtain measurements of the signals, such as, but not limited to, Ec / Io, SNR, RSRP, RSSI, etc. Transmitter 708 may include hardware, firmware, and / or processor-executable software code for transmitting data, the code comprising instructions and stored in memory (e.g., a computer-readable medium). Suitable examples of transmitter 708 may include, but are not limited to, RF transmitters.

[0089] Furthermore, in one aspect, the transmitting device may include an RF front-end 788, which is communicatively operable with one or more antennas 765 and a transceiver 702 for receiving and transmitting radio transmissions, such as wireless communications transmitted by at least one base station 102 or wireless transmissions transmitted by a UE 104. The RF front-end 788 may be connected to one or more antennas 765 and may include one or more low-noise amplifiers (LNAs) 790, one or more switches 792, one or more power amplifiers (PAs) 798, and one or more filters 796 for transmitting and receiving RF signals.

[0090] On one hand, the LNA 790 can amplify the received signal to a desired output level. On another hand, each LNA 790 can have specified minimum and maximum gain values. On yet another hand, the RF front end 788 can use one or more switches 592 to select a particular LNA 790 and its specified gain value based on the desired gain value for a particular application.

[0091] Furthermore, for example, one or more PAs 798 may be used by the RF front end 788 to amplify signals to obtain an RF output with a desired output power level. In one aspect, each PA 798 may have specified minimum and maximum gain values. In another aspect, the RF front end 788 may use one or more switches 792 to select a particular PA 798 and its specified gain value based on the desired gain value for a particular application.

[0092] Furthermore, for example, one or more filters 796 may be used by the RF front end 788 to filter the received signal to obtain the input RF signal. Similarly, in one aspect, for example, a corresponding filter 796 may be used to filter the output from a corresponding PA 798 to produce an output signal for transmission. In one aspect, each filter 796 may be connected to a specific LNA 790 and / or PA 798. In one aspect, the RF front end 788 may use one or more switches 792 to select the transmit or receive path using a specified filter 796, LNA 790, and / or PA 798 based on a configuration as specified by the transceiver 702 and / or processor 712.

[0093] Thus, transceiver 702 can be configured to transmit and receive wireless signals via RF front end 788 through one or more antennas 765. In one aspect, transceiver 702 can be tuned to operate at a specified frequency so that the transmitting device can, for example, communicate with one or more base stations 102 or one or more cells associated with one or more base stations 102 or other UE 104. In another aspect, for example, modem 714 can configure transceiver 702 to operate at a specified frequency and power level based on the configuration of the transmitting device and the communication protocol used by modem 714.

[0094] In one aspect, modem 714 may be a multi-band, multi-mode modem capable of processing digital data and communicating with transceiver 702 to enable the use of transceiver 702 to transmit and receive digital data. In another aspect, modem 714 may be multi-band and configured to support multiple frequency bands for a specific communication protocol. In another aspect, modem 714 may be multi-mode and configured to support multiple operating networks and communication protocols. In one aspect, modem 714 may control one or more components of the transmitting device (e.g., RF front-end 788, transceiver 702) to enable signal transmission and / or reception with the network based on a specified modem configuration. In one aspect, the modem configuration may be based on the mode and frequency band used by modem 714. In another aspect, the modem configuration may be based on UE configuration information associated with the transmitting device, such as information provided by the network during cell selection and / or cell reselection.

[0095] Reference Figure 8 Example methods 800 for wireless communication according to various aspects of this disclosure can be found by reference. Figure 1-6 One or more UEs 104 are discussed for implementation. Although method 800 is described below with respect to the various elements of UE 104, other components may also be used to implement one or more of the steps described herein.

[0096] In block 805, method 800 may include receiving conditional handover configuration information from a source base station at a first user equipment (UE), wherein the conditional handover configuration information partially includes conditional handover execution criteria that should be met by the first UE to perform a conditional handover. Aspects of block 805 may be derived from receiving, as referenced... Figure 7 The transceiver 702 describes the operation of detecting signals on one or more antennas 765. The detected signals are filtered by the RF front-end 788 of the UE 104 and forwarded to the modem 714 for processing by the conditional handover configuration component 750. Thus, one or more antennas 765, transceiver 702, conditional handover configuration component 750, modem 714, processor 712 and / or UE 104 or one of its sub-components can define means for receiving conditional handover configuration information from the source base station at the first user equipment (UE).

[0097] In some examples, the first UE may be in communication with the source base station via a direct communication path before a conditional handover is triggered. In this scenario, the conditional handover configuration information may include information about multiple candidate relay UEs prepared by the target base station for the first UE to select from for a relay path to that target base station.

[0098] In block 810, method 800 may include determining, at the first UE, that the conditional handover execution criterion is met based in part on one of the channel conditions between the first UE and the source base station falling below a channel conditions threshold or the sidelink channel conditions between the first UE and the second UE falling below a sidelink channel conditions threshold. Aspects of block 810 may also be performed by conditional handover configuration component 750. Thus, one or more antennas 765, transceiver 702, conditional handover configuration component 750, modem 714, processor 712, and / or UE 104 or one of its sub-components may define means for determining, at the first UE, that the conditional handover execution criterion is met based in part on one of the channel conditions between the first UE and the source base station falling below a channel conditions threshold or the sidelink channel conditions between the first UE and the second UE falling below a sidelink channel conditions threshold.

[0099] In some respects, the first UE may communicate with the source base station via a relay path before triggering a conditional handover. In this case, determining that the conditional handover execution criteria are met may include measuring the sidelink reference signal received power (SL-RSRP) between the first UE and the second UE and determining that the SL-RSRP drops below a sidelink channel condition threshold.

[0100] In block 815, method 800 may include triggering a conditional handover at a first UE to transfer communication from a source base station to a target base station via a direct communication path or a relay path. Aspects of block 810 may also be performed by conditional handover configuration component 750. Thus, one or more antennas 765, transceiver 702, conditional handover configuration component 750, modem 714, processor 712, and / or UE 104 or one of its sub-components may define means for triggering a conditional handover at a first UE to transfer communication from a source base station to a target base station via a direct communication path or a relay path.

[0101] In some examples, triggering a conditional handover at the first UE to switch communication from the source base station to the target base station may include maintaining communication with the source base station while a target path to the target base station is established via a direct communication path or a relay path.

[0102] In some aspects, the first UE may be a relay UE that enables one or more remote UEs to communicate with the source base station before triggering a conditional handover. Thus, triggering a conditional handover at the first UE to transfer communication from the source base station to the target base station may include receiving a remote UE handover command from the source base station at the first UE as part of conditional handover configuration information. The first UE may then transmit the remote UE handover command from the first UE to one or more remote UEs upon triggering the conditional handover, wherein the one or more remote UEs reconfigure their connection to the target base station via the first UE.

[0103] In some examples, the method may include selecting a relay UE from a plurality of candidate relay UEs prepared by the target base station for the first UE based in part on a measurement of the sidelink discovery reference signal received power (SD-RSRP) between the first UE and each of the plurality of candidate relay UEs.

[0104] Figure 9 The document describes hardware components and sub-components of an apparatus (which may be base station 102) for implementing one or more methods (e.g., method 1000) described herein, according to various aspects of this disclosure. In some examples, base station 102 may be configured as described in reference... Figure 1-6 The described source or target base station for conditional handover. For example, an example implementation of base station 102 may include a variety of components, some of which have already been described above, but also include components such as one or more processors 912, memory 916, and transceiver 902 that are in communication via one or more buses 844, which may operate in conjunction with handover component 950 to implement the functionality described herein in relation to one or more methods (e.g., 900) including this disclosure.

[0105] In some respects, the handover component 950 is configured to configure and initiate handover procedures to move UE 104 and UE 106 to another base station (or vice versa). For example, the handover component 950 may receive one or more measurement reports from UE 104 and / or UE 106, and may determine, at least in part, whether to initiate a handover procedure and whether to identify a conditional handover execution trigger for one or more UEs based on the measurement reports.

[0106] One or more processors 912, modems 914, memory 916, transceivers 902, RF front-ends 988, and one or more antennas 965 may be configured to support voice and / or data calls (simultaneously or asynchronously) in one or more radio access technologies. In one aspect, the one or more processors 912 may include modems 914 using one or more modem processors. Various functions associated with the switching component 950 may be included in modems 914 and / or processors 912, and in one aspect, may be performed by a single processor, while in other aspects, different functions may be performed by a combination of two or more different processors. For example, in one aspect, the one or more processors 912 may include any one or any combination of: a modem processor, or a baseband processor, or a digital signal processor, or a transmitter processor, or a receiver processor, or a transceiver processor associated with transceiver 902. In other aspects, some features of the one or more processors 912 and / or modems 914 associated with the switching component 950 may be performed by transceiver 902.

[0107] Memory 916 may be configured to store data used herein and / or a local version of application 975, or one or more of switching components 950 and / or their sub-components executed by at least one processor 912. Memory 916 may include any type of computer-readable medium that can be used by a computer or at least one processor 912, such as random access memory (RAM), read-only memory (ROM), tape, magnetic disk, optical disk, volatile memory, non-volatile memory, and any combination thereof. In one aspect, for example, when base station 102 is operating at least one processor 912 to execute switching component 950 and / or one or more of its sub-components, memory 916 may be a non-transient computer-readable storage medium storing one or more computer-executable codes defining switching component 950 and / or one or more of its sub-components and / or associated data.

[0108] Transceiver 902 may include at least one receiver 906 and at least one transmitter 908. Receiver 906 may include hardware, firmware, and / or processor-executable software code for receiving data, the code comprising instructions and stored in memory (e.g., a computer-readable medium). Receiver 906 may be, for example, a radio frequency (RF) receiver. In one aspect, receiver 906 may receive signals transmitted by at least one UE 104. Additionally, receiver 906 may process such received signals and may also obtain measurements of the signals, such as, but not limited to, Ec / Io, SNR, RSRP, RSSI, etc. Transmitter 908 may include hardware, firmware, and / or processor-executable software code for transmitting data, the code comprising instructions and stored in memory (e.g., a computer-readable medium). Suitable examples of transmitter 908 may include, but are not limited to, RF transmitters.

[0109] Furthermore, in one aspect, the transmitting device may include an RF front-end 988, which is communicatively operable with one or more antennas 965 and a transceiver 902 for receiving and transmitting radio transmissions, such as wireless communications transmitted by UE 104. The RF front-end 988 may be connected to one or more antennas 965 and may include one or more low-noise amplifiers (LNAs) 990, one or more switches 992, one or more power amplifiers (PAs) 998, and one or more filters 996 for transmitting and receiving RF signals.

[0110] On one hand, the LNA 990 can amplify the received signal to a desired output level. On another hand, each LNA 990 can have specified minimum and maximum gain values. On yet another hand, the RF front end 988 can use one or more switches 992 to select a particular LNA 990 and its specified gain value based on the desired gain value for a particular application.

[0111] Furthermore, for example, one or more PAs 998 may be used by an RF front-end 988 to amplify signals to obtain an RF output with a desired output power level. In one aspect, each PA 998 may have specified minimum and maximum gain values. In another aspect, the RF front-end 988 may use one or more switches 992 to select a particular PA 998 and its specified gain value based on the desired gain value for a particular application.

[0112] Furthermore, for example, one or more filters 996 may be used by the RF front end 988 to filter the received signal to obtain the input RF signal. Similarly, in one aspect, for example, a corresponding filter 996 may be used to filter the output from a corresponding PA 998 to produce an output signal for transmission. In one aspect, each filter 996 may be connected to a specific LNA 990 and / or PA 998. In one aspect, the RF front end 988 may use one or more switches 992 to select the transmit or receive path using a specified filter 996, LNA 990, and / or PA 998 based on a configuration as specified by the transceiver 902 and / or processor 912.

[0113] Thus, transceiver 902 can be configured to transmit and receive wireless signals via RF front end 788 through one or more antennas 965. In one aspect, transceiver 902 can be tuned to operate at a specified frequency so that the transmitting device can, for example, communicate with one or more UEs 104. In another aspect, for example, modem 914 can configure transceiver 902 to operate at a specified frequency and power level based on the configuration of the transmitting device and the communication protocol used by modem 914.

[0114] In one aspect, modem 914 may be a multi-band, multi-mode modem capable of processing digital data and communicating with transceiver 902 to enable the use of transceiver 902 to transmit and receive digital data. In another aspect, modem 914 may be multi-band and configured to support multiple frequency bands for a specific communication protocol. In another aspect, modem 914 may be multi-mode and configured to support multiple operating networks and communication protocols. In one aspect, modem 914 may control one or more components of the transmitting device (e.g., RF front-end 988, transceiver 902) to achieve signal transmission and / or reception with the network based on a specified modem configuration. In one aspect, the modem configuration may be based on the mode and frequency band used by modem 914. In another aspect, the modem configuration may be based on base station configuration information associated with the transmitting device, such as information provided by the network during cell selection and / or cell reselection.

[0115] Reference Figure 10 Example method 1000 for wireless communication according to various aspects of this disclosure can be obtained by referring to Figure 1-6 One or more base stations 102 are discussed for implementation. Although method 1000 is described below with respect to the various elements of base station 102, other components may also be used to implement one or more of the steps described herein.

[0116] In block 1005, method 1000 may include receiving a measurement report from a first user equipment (UE) at a source base station, wherein the measurement report indicates the signal quality between the first UE and the source base station. Aspects of block 1005 may be determined by receiving, as referenced... Figure 9 Transceiver 905 performs the function of detecting signals on one or more antennas 965. The detected signals are filtered by the RF front-end 988 of base station 102 and forwarded to modem 914 for processing by switching component 950. Thus, one or more antennas 965, transceiver 902, switching component 950, modem 914, processor 912 and / or base station 102 or one of its sub-components can define means for receiving a measurement report from a first user equipment (UE) at the source base station, wherein the measurement report indicates the signal quality between the first UE and the source base station.

[0117] In block 1010, method 1000 may include identifying one or more candidate target base stations for a first UE to switch communication from a source base station to, wherein the one or more candidate target base stations prepare multiple relay UEs within the coverage area of ​​the one or more candidate target base stations for the first UE. In some aspects, the one or more candidate target base stations also prepare conditional handover cells for one or more remote UEs communicating with the first UE. Aspects of block 1010 may be referenced from... Figure 9 The described switching component 950 performs this action. Thus, one or more antennas 965, transceiver 902, switching component 950, modem 914, processor 912, and / or base station 102 or one of their sub-components may define means for identifying one or more candidate target base stations to which the first UE will switch communication from a source base station, wherein the one or more candidate target base stations prepare multiple relay UEs within the coverage area of ​​the one or more candidate target base stations for the first UE.

[0118] In block 1015, method 1000 may include generating conditional handover configuration information for a first UE, partially based on identifying the one or more candidate target base stations, wherein the conditional handover configuration information partially includes conditional handover execution criteria that the first UE should satisfy to perform a conditional handover. In some examples, the conditional handover configuration information may further include a remote UE handover command for the first UE to forward to one or more remote UEs when a conditional handover is triggered. Aspects of block 1010 may be referenced from Figure 9 The described handover component 950 performs this action. Thus, one or more antennas 965, transceiver 902, handover component 950, modem 914, processor 912, and / or base station 102 or one of their sub-components may define means for generating conditional handover configuration information for a first UE, partially based on identifying the one or more candidate target base stations.

[0119] In some aspects, method 1000 may further include configuring internal conditional handover preparation for a first UE at a source base station, wherein the internal conditional handover preparation includes identifying one or more internal candidate relay UEs for the first UE that are located within the coverage area of ​​the source base station.

[0120] In block 1020, method 1000 may include transmitting conditional handover configuration information to a first UE. Aspects of block 1020 may be determined by receiving, as referenced... Figure 9 The transceiver 905 describes the operation of detecting signals on one or more antennas 965. The detected signals are filtered by the RF front-end 988 of the base station 102 and forwarded to the modem 914 for processing by the handover component 950. Thus, one or more antennas 965, transceiver 902, handover component 950, modem 914, processor 912 and / or base station 102 or one of its sub-components can define means for transmitting conditional handover configuration information to the first UE.

[0121] In some examples, the method may further include receiving from the first UE an indication of a relay UE selected from a plurality of relay UEs prepared for the first UE and identified in conditional handover configuration information, and releasing the first UE context from the plurality of relay UEs that were not selected.

[0122] The detailed description above, in conjunction with the accompanying drawings, describes examples and does not represent only examples that can be implemented or fall within the scope of the claims. The term "example" as used in this description means "serving as an example, instance, or illustration," and not "superior to" or "better than other examples." This detailed description includes specific details to provide an understanding of the described techniques. However, these techniques may be practiced without these specific details. In some instances, well-known structures and devices are shown in block diagram form to avoid obscuring the concepts of the described examples.

[0123] Information and signals can be represented using any of a wide variety of different techniques and technologies. For example, data, instructions, commands, information, signals, bits, symbols, and chips, which may be referred to throughout the above description, can be represented by voltage, current, electromagnetic waves, magnetic fields or magnetic particles, light fields or light particles, computer-executable code or instructions stored on a computer-readable medium, or any combination thereof.

[0124] The various explanatory frames and components described herein can be implemented or executed using specially programmed devices, such as, but not limited to, processors, digital signal processors (DSPs), ASICs, FPGAs, or other programmable logic devices designed to perform the functions described herein, discrete gate or transistor logic, discrete hardware components, or any combination thereof. A specially programmed processor may be a microprocessor, but in alternatives, the processor may be any conventional processor, controller, microcontroller, or state machine. A specially programmed processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors cooperating with a DSP core, or any other such configuration.

[0125] The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions may be stored as one or more instructions or codes on or transmitted via a non-transient computer-readable medium. Other examples and implementations fall within the scope and spirit of this disclosure and the appended claims. For example, due to the nature of software, the functions described above may be implemented using software, hardware, firmware, hardwired, or any combination thereof executed by a specially programmed processor. Features implementing the functions may also be physically located in various locations, including being distributed such that portions of the functions are implemented at different physical locations. Moreover, as used herein (including in the claims), the "or" used in a list of items followed by "at least one of" indicates a disjunctive enumeration, such that an enumeration such as "at least one of A, B, or C" represents A or B or C or AB or AC or BC or ABC (i.e., A and B and C).

[0126] Computer-readable media includes both computer storage media and communication media, encompassing any medium that facilitates the transfer of a computer program from one location to another. Storage media can be any available medium accessible to a general-purpose or special-purpose computer. By way of example and not limitation, computer-readable media may include RAM, ROM, EEPROM, CD-ROM or other optical disc storage, disk storage or other magnetic storage devices, or any other medium capable of carrying or storing desired program code in the form of instructions or data structures and accessible to a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor. Similarly, any connection is also legitimately referred to as computer-readable media. For example, if software is transmitted from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then such coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of media. As used in this article, disk and disc include compact discs (CDs), laser discs, optical discs, digital multi-purpose discs (DVDs), floppy disks, and Blu-ray discs. Disks often magnetically reproduce data, while discs optically reproduce data using lasers. Combinations of these media are also included within the scope of computer-readable media.

[0127] The detailed description above, taken in conjunction with the accompanying drawings, is intended to describe various configurations and is not intended to represent the only configuration in which the concepts described herein can be practiced. This detailed description includes specific details to provide a thorough understanding of the various concepts. However, it will be apparent to those skilled in the art that these concepts can be practiced without these specific details. In some instances, well-known structures and components are shown in block diagram form to avoid obscuring such concepts.

[0128] Various apparatuses and methods are also described with reference to several aspects of the telecommunications system. These apparatuses and methods are described in detail and illustrated in the accompanying drawings by various blocks, components, circuits, processes, algorithms, etc. (collectively referred to as “elements”). These elements can be implemented using electronic hardware, computer software, or any combination thereof. Whether such elements are implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system.

[0129] As an example, an element, or any part of an element, or any combination of elements, may be implemented as a "processing system" including one or more processors. Examples of processors include: microprocessors, microcontrollers, graphics processing units (GPUs), central processing units (CPUs), application processors, digital signal processors (DSPs), reduced instruction set computing (RISC) processors, system-on-a-chip (SoCs), baseband processors, field-programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functionalities described throughout this disclosure. One or more processors in a processing system can execute software. Software should be broadly interpreted as instructions, instruction sets, code, code segments, program code, programs, subroutines, software components, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description languages, or other terms.

[0130] It should be noted that the techniques described herein can be used in various wireless communication networks, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and other systems. The terms "system" and "network" are often used interchangeably. CDMA systems can implement radio technologies such as CDMA2000 and Universal Terrestrial Radio Access (UTRA). CDMA2000 encompasses the IS-2000, IS-95, and IS-856 standards. IS-2000 versions 0 and A are commonly referred to as CDMA2000 1X, 1X, etc. IS-856 (TIA-856) is commonly referred to as CDMA2000 1xEV-DO, High Rate Packet Data (HRPD), etc. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. TDMA systems can implement radio technologies such as Global System for Mobile Communications (GSM). OFDMA systems can implement technologies such as Ultra Mobile Broadband (UMB), Evolved UTRA (E-UTRA), IEEE 902.11 (Wi-Fi), IEEE 902.16 (WiMAX), IEEE 902.20, and Flash-OFDM. TMRadio technologies such as UTRA and E-UTRA are part of the Universal Mobile Telecommunications System (UMTS). 3GPP Long Term Evolution (LTE) and LTE-A Advanced (LTE-A) are new UMTS versions using E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, and GSM are described in documents from an organization called the Third Generation Partnership Project (3GPP). CDMA2000 and UMB are described in documents from an organization called the Third Generation Partnership Project 2 (3GPP2). The technologies described herein can be used with the systems and radio technologies mentioned above, as well as with other systems and radio technologies, including cellular (e.g., LTE) communications sharing a RF band. However, the following description describes LTE / LTE-A and / or 5G New Radio (NR) systems for illustrative purposes, and the terms LTE or 5G NR are used in most of the following description, but these technologies can also be applied beyond LTE / LTE-A and 5G NR applications (e.g., to other next-generation communication systems).

[0131] The prior description of this disclosure is provided to enable those skilled in the art to make or use it. Various modifications to this disclosure will readily be apparent to those skilled in the art, and the common principles defined herein can be applied to other variations without departing from the spirit or scope of this disclosure. Furthermore, although elements of the described aspects and / or embodiments may be described or claimed in the singular, the plural is also contemplated unless explicitly stated to be limited to the singular. Additionally, all or part of any aspect and / or embodiment may be used in conjunction with all or part of any other aspect and / or embodiment unless otherwise stated. Thus, this disclosure is not limited to the examples and designs described herein, but should be accorded the widest scope consistent with the principles and novel features disclosed herein.

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Claims

1. A method for wireless communication, comprising: Conditional handover configuration information is received from the source network entity at the first user equipment (UE), wherein the conditional handover configuration information includes in part a conditional handover execution criterion that should be met by the first UE to perform a conditional handover. At the first UE, the conditional handover execution criterion is determined to be satisfied based in part on one of the following: the channel condition between the first UE and the source network entity drops below a channel condition threshold, or the sidelink channel condition between the first UE and the second UE drops below a sidelink channel condition threshold. as well as The conditional handover is triggered at the first UE to transfer communication from the source network entity to the target network entity via a direct communication path or a relay path. The first UE is in communication with the source network entity via the direct communication path before triggering the conditional handover, and the conditional handover configuration information includes information about a plurality of candidate relay UEs prepared by the target network entity for the first UE to select from for the relay path to the target network entity. or Wherein the first UE is a relay UE that enables one or more remote UEs to communicate with the source network entity before triggering the conditional handover, and triggering the conditional handover at the first UE to switch communication from the source network entity to the target network entity includes: receiving a remote UE handover command from the source network entity at the first UE as part of the conditional handover configuration information; And, upon triggering the conditional handover, transmitting the remote UE handover command from the first UE to the one or more remote UEs, wherein the one or more remote UEs are reconfigured to the connection to the target network entity via the first UE.

2. The method of claim 1, further comprising: The relay UE is selected from the plurality of candidate relay UEs prepared by the target network entity for the first UE, in part based on the measurement of the sidelink discovery reference signal received power (SD-RSRP) between the first UE and each of the plurality of candidate relay UEs.

3. The method of claim 1, wherein the first UE is in communication with the source network entity via the relay path prior to triggering the conditional handover.

4. The method of claim 3, wherein determining that the conditional switching execution criterion is satisfied includes: Measure the side link reference signal received power (SL-RSRP) between the first UE and the second UE; as well as It is determined that the SL-RSRP has fallen below the sidelink channel condition threshold.

5. The method of claim 1, wherein triggering the conditional handover at the first UE to switch communication from the source network entity to the target network entity comprises: Communication with the source network entity is maintained when a target path to the target network entity is established via the direct communication path or the relay path.

6. An apparatus for wireless communication, comprising: At least one processor; and a memory coupled to the at least one processor, the memory including instructions executable by the at least one processor to cause the device to: Conditional handover configuration information is received from the source network entity at the first user equipment (UE), wherein the conditional handover configuration information includes in part a conditional handover execution criterion that should be met by the first UE to perform a conditional handover. At the first UE, the conditional handover execution criterion is determined to be satisfied based in part on one of the following: the channel condition between the first UE and the source network entity drops below a channel condition threshold, or the sidelink channel condition between the first UE and the second UE drops below a sidelink channel condition threshold. as well as The conditional handover is triggered at the first UE to transfer communication from the source network entity to the target network entity via a direct communication path or a relay path. The first UE is in communication with the source network entity via the direct communication path before triggering the conditional handover, and the conditional handover configuration information includes information about a plurality of candidate relay UEs prepared by the target network entity for the first UE to select from for the relay path to the target network entity. or Wherein the first UE is a relay UE that enables one or more remote UEs to communicate with the source network entity before triggering the conditional handover, and triggering the conditional handover at the first UE to switch communication from the source network entity to the target network entity includes: receiving a remote UE handover command from the source network entity at the first UE as part of the conditional handover configuration information; And, upon triggering the conditional handover, transmitting the remote UE handover command from the first UE to the one or more remote UEs, wherein the one or more remote UEs are reconfigured to the connection to the target network entity via the first UE.

7. The apparatus of claim 6, wherein the processor is further configured to execute instructions to perform any one of the methods of claims 2-5.

8. A non-transient computer-readable medium storing instructions executable by a processor for wireless communication, comprising instructions for the following operations: Conditional handover configuration information is received from the source network entity at the first user equipment (UE), wherein the conditional handover configuration information includes in part a conditional handover execution criterion that should be met by the first UE to perform a conditional handover. At the first UE, the conditional handover execution criterion is determined to be satisfied based in part on one of the following: the channel condition between the first UE and the source network entity drops below a channel condition threshold, or the sidelink channel condition between the first UE and the second UE drops below a sidelink channel condition threshold. as well as The conditional handover is triggered at the first UE to transfer communication from the source network entity to the target network entity via a direct communication path or a relay path. The first UE is in communication with the source network entity via the direct communication path before triggering the conditional handover, and the conditional handover configuration information includes information about a plurality of candidate relay UEs prepared by the target network entity for the first UE to select from for the relay path to the target network entity. or Wherein the first UE is a relay UE that enables one or more remote UEs to communicate with the source network entity before triggering the conditional handover, and triggering the conditional handover at the first UE to switch communication from the source network entity to the target network entity includes: receiving a remote UE handover command from the source network entity at the first UE as part of the conditional handover configuration information; And, upon triggering the conditional handover, transmitting the remote UE handover command from the first UE to the one or more remote UEs, wherein the one or more remote UEs are reconfigured to the connection to the target network entity via the first UE.

9. The non-transient computer-readable medium of claim 8, wherein the processor further comprises instructions for performing any of the methods of claims 2-5.

10. A device for wireless communication, comprising: A means for receiving conditional handover configuration information from a source network entity at a first user equipment (UE), wherein the conditional handover configuration information includes in part conditional handover execution criteria that should be met by the first UE to perform a conditional handover. A means for determining, at the first UE, that the conditional handover execution criterion is satisfied, in part based on either the channel condition between the first UE and the source network entity falling below a channel condition threshold or the sidelink channel condition between the first UE and the second UE falling below a sidelink channel condition threshold; as well as A means for triggering the conditional handover at the first UE to transfer communication from the source network entity to the target network entity via a direct communication path or a relay path. The first UE is in communication with the source network entity via the direct communication path before triggering the conditional handover, and the conditional handover configuration information includes information about a plurality of candidate relay UEs prepared by the target network entity for the first UE to select from for the relay path to the target network entity. or Wherein the first UE is a relay UE for one or more remote UEs to communicate with the source network entity before triggering the conditional handover, and the means for triggering the conditional handover at the first UE to switch communication from the source network entity to the target network entity includes: means for receiving a remote UE handover command from the source network entity at the first UE as part of the conditional handover configuration information; And means for transmitting the remote UE handover command from the first UE to the one or more remote UEs when the conditional handover is triggered, wherein the one or more remote UEs are reconfigured to the connection of the target network entity via the first UE.

11. The apparatus of claim 10, further comprising means for performing any one of the methods of claims 2-5.

12. A method for wireless communication, comprising: A measurement report is received from a first user equipment (UE) at the source network entity, wherein the measurement report indicates the signal quality between the first UE and the source network entity; Identify one or more candidate target network entities to which the first UE will transfer communication from the source network entity, wherein the one or more candidate target network entities are multiple candidate relay UEs that the first UE is preparing to be within the coverage area of ​​the one or more candidate target network entities; Conditional handover configuration information for the first UE is generated in part based on identifying one or more candidate target network entities, wherein the conditional handover configuration information includes conditional handover execution criteria that the first UE should meet to perform conditional handover and identifies the plurality of candidate relay UEs prepared for the first UE by the one or more candidate target network entities; as well as The conditional handover configuration information is transmitted to the first UE.

13. The method of claim 12, further comprising: Configure internal conditional handover preparation for the first UE at the source network entity, wherein the internal conditional handover preparation includes identifying one or more internal candidate relay UEs for the first UE that are located within the coverage area of ​​the source network entity.

14. The method of claim 12, further comprising: After the first UE initiates a conditional handover, communication between the first UE and the source network entity is maintained, wherein the communication between the first UE and the source network entity is maintained when a target path from the first UE to the target network entity is established via a direct communication path or a relay path.

15. The method of claim 12, wherein the one or more candidate target network entities further prepare conditional handover cells for one or more remote UEs communicating with the first UE.

16. The method of claim 12, further comprising: The first UE receives an indication of the selected relay UE from the plurality of candidate relay UEs that have been prepared for the first UE and identified in the conditional handover configuration information; as well as Multiple candidate relay UEs that were never selected release the first UE context.

17. The method of claim 12, wherein the conditional handover configuration information further includes a remote UE handover command for the first UE to forward to one or more remote UEs when a conditional handover is triggered.

18. An apparatus for wireless communication, comprising: At least one processor; and a memory coupled to the at least one processor, the memory including instructions executable by the at least one processor to cause the device to: A measurement report is received from a first user equipment (UE) at the source network entity, wherein the measurement report indicates the signal quality between the first UE and the source network entity; Identify one or more candidate target network entities to which the first UE will transfer communication from the source network entity, wherein the one or more candidate target network entities are multiple candidate relay UEs that the first UE is preparing to be within the coverage area of ​​the one or more candidate target network entities; Conditional handover configuration information for the first UE is generated in part based on identifying one or more candidate target network entities, wherein the conditional handover configuration information includes conditional handover execution criteria that the first UE should meet to perform conditional handover and identifies the plurality of candidate relay UEs prepared for the first UE by the one or more candidate target network entities; as well as The conditional handover configuration information is transmitted to the first UE.

19. The apparatus of claim 18, wherein the processor is further configured to execute instructions to perform any of the methods of claims 13-17.

20. A non-transient computer-readable medium storing instructions executable by a processor for wireless communication, comprising instructions for the following operations: A measurement report is received from a first user equipment (UE) at the source network entity, wherein the measurement report indicates the signal quality between the first UE and the source network entity; Identify one or more candidate target network entities to which the first UE will transfer communication from the source network entity, wherein the one or more candidate target network entities are multiple candidate relay UEs that the first UE is preparing to be within the coverage area of ​​the one or more candidate target network entities; Conditional handover configuration information for the first UE is generated in part based on identifying one or more candidate target network entities, wherein the conditional handover configuration information includes conditional handover execution criteria that the first UE should meet to perform conditional handover and identifies the plurality of candidate relay UEs prepared for the first UE by the one or more candidate target network entities; as well as The conditional handover configuration information is transmitted to the first UE.

21. The non-transient computer-readable medium of claim 20, wherein the processor further comprises instructions for performing any of the methods of claims 13-17.

22. A device for wireless communication, comprising: A means for receiving a measurement report from a first user equipment (UE) at a source network entity, wherein the measurement report indicates the signal quality between the first UE and the source network entity; A means for identifying one or more candidate target network entities to which the first UE will transfer communication from the source network entity, wherein the one or more candidate target network entities are multiple candidate relay UEs that the first UE is preparing to be located within the coverage area of ​​the one or more candidate target network entities; A means for generating conditional handover configuration information for the first UE based in part on identifying the one or more candidate target network entities, wherein the conditional handover configuration information includes in part a conditional handover execution criterion that the first UE should satisfy to perform a conditional handover and identifies the plurality of candidate relay UEs prepared for the first UE by the one or more candidate target network entities; as well as A means for transmitting the conditional handover configuration information to the first UE.

23. The apparatus of claim 22, further comprising means for performing any of the methods of claims 13-17.

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