Continuous conditional switching

Abstract

The present disclosure relates to continuous conditional handovers. The present disclosure relates to techniques for performing continuous conditional handovers. A cellular base station may provide conditional handover information for multiple conditional handovers to a wireless device. The conditional handover information may include information for performing a conditional handover from a cell provided by the cellular base station to at least one cell and information for performing a conditional handover from one or more of the cells to at least one cell. The wireless device may perform multiple continuous conditional handovers using the conditional handover information.

Description

Technical Field

[0001] The present application relates to wireless communications, and more particularly to systems, apparatus, and methods for performing continuous conditional handover. Background Art

[0002] The use of wireless communication systems is growing rapidly. In recent years, wireless devices such as smartphones and tablets have become increasingly sophisticated. In addition to supporting phone calls, many mobile devices (e.g., user equipment devices or UEs) now also provide access to the Internet, email, text messaging, and navigation using a global positioning system (GPS), and are capable of operating complex and sophisticated applications that utilize these capabilities. In addition, there are a number of different wireless communication technologies and standards. Some examples of wireless communication standards include GSM, UMTS (e.g., associated with WCDMA or TD-SCDMA air interfaces), 5G NR, LTE, Advanced LTE (LTE-A), HSPA, 3GPP2 CDMA2000 (e.g., 1xRTT, 1xEV-DO, HRPD, eHRPD), IEEE 802.11 (WLAN or Wi-Fi), BLUETOOTH TM wait.

[0003] The introduction of an ever-increasing number of features and functions in wireless communication devices has also created a continuing need for improved wireless communications and improved wireless communication devices. In particular, it is important to ensure the accuracy of transmitted and received signals by wireless devices used in wireless cellular communications. In addition, increasing the functionality of UE devices may place significant pressure on the battery life of UE devices. Therefore, it is also very important to reduce the power requirements in UE device design while allowing the UE device to maintain good transmit and receive capabilities to improve communications.

[0004] In order to increase coverage and better serve the increased demand and range of intended uses of wireless communications, in addition to the above-mentioned communication standards, there are wireless communication technologies being developed, including fifth generation (5G) new radio (NR) communications. Therefore, there is a need for improvements in the field of supporting such development and design. Summary of the invention

[0005] Embodiments of apparatus, systems, and methods for performing continuous conditional switching are provided herein.

[0006] According to the technology described herein, a cellular base station may configure a wireless device served by the cellular base station with information that supports possible early conditional handovers to multiple cells. Specifically, conditional handover information that can support multiple consecutive conditional handovers (such as from a service cell provided by a cellular base station to another cell, and from the other cell to yet another cell) may be obtained by the cellular base station using conditional handover requests to other cellular base stations. The conditional handover information may be provided to the wireless device as part of a conditional handover command, and when a condition indicated in the conditional handover information is met, the wireless device may use the conditional handover information to perform the conditional handover. The wireless device may retain the conditional handover information after performing the conditional handover, so that the wireless device may use the same conditional handover information to perform one or more other conditional handovers, for example, similarly, if the condition indicated in the conditional handover information is met.

[0007] Such techniques can help minimize handover signaling and improve handover reliability, especially in high-speed / high-mobility / high-density scenarios where timely signaling may be susceptible to rapidly changing channel conditions, and can also help reduce data losses, gaps, and pauses, which, at least according to some embodiments, may be caused by such less reliable handover operations.

[0008] It should be noted that the techniques described herein may be implemented in and / or used with a number of different types of devices, including but not limited to base stations, access points, cellular telephones, portable media players, tablet computers, wearable devices, and various other computing devices.

[0009] This disclosure is intended to provide a brief overview of some of the topics described in this document. Therefore, it should be understood that the above features are only examples and should not be interpreted as narrowing the scope or essence of the topics described herein in any way. Other features, aspects and advantages of the topics described herein will become apparent through the following detailed description, drawings and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] A better understanding of the present subject matter may be obtained when the following detailed description of the embodiments is considered in conjunction with the following drawings.

[0011] Figure 1 An exemplary (and simplified) wireless communication system according to some embodiments is shown;

[0012] Figure 2 illustrates an exemplary base station in communication with an exemplary wireless user equipment (UE) device in accordance with some embodiments;

[0013] Figure 3shows an exemplary block diagram of a UE according to some embodiments;

[0014] Figure 4 shows an exemplary block diagram of a base station according to some embodiments;

[0015] Figure 5 is a signal flow diagram illustrating aspects of an exemplary possible method for performing continuous conditional handover according to some embodiments;

[0016] Figure 6 to Figure 7 is a signal flow diagram illustrating aspects of exemplary possible scenarios in which handover failures may occur according to some embodiments;

[0017] Figure 8 is a signal flow diagram illustrating aspects of an exemplary possible scenario using a conditional switch command;

[0018] Figures 9 and 10 illustrates other aspects of exemplary possible scenarios in which handover failures may occur according to some embodiments;

[0019] Figure 11 to Figure 12 is a signal flow diagram illustrating aspects of an exemplary possible method of configuring a wireless device to perform continuous conditional handover according to some embodiments;

[0020] Fig.13 Other aspects of an exemplary possible scenario in which a wireless device is configured to perform continuous conditional handover according to some embodiments are shown;

[0021] Figure 14 to Figure 15 is a signal flow diagram illustrating aspects of an exemplary possible scenario in which a handover command is provided to a wireless device that has been configured to perform continuous conditional handover according to some embodiments; and

[0022] Fig.16 is a signal flow diagram illustrating aspects of an exemplary possible scenario in which a wireless device provides information indicating whether the wireless device supports the capability of continuous conditional handover according to some embodiments.

[0023] Although the features described herein are susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and described in detail herein. However, it should be understood that the drawings and detailed description thereof are not intended to limit this document to the specific forms disclosed, but on the contrary, their purpose is to cover all modifications, equivalents and alternatives that fall within the spirit and scope of the subject matter as defined by the appended claims. DETAILED DESCRIPTION

[0024] Acronyms

[0025] Various acronyms are used throughout this application. The definitions of the most prominent acronyms used that may appear throughout this application are as follows:

[0026] UE: User Equipment

[0027] RF: Radio Frequency

[0028] BS: Base Station

[0029] GSM: Global System for Mobile Communications

[0030] UMTS: Universal Mobile Telecommunications System

[0031] LTE: Long Term Evolution

[0032] Nr: New radio component

[0033] TX: Transmit

[0034] RX: Receive

[0035] RAT: Radio Access Technology

[0036] the term

[0037] The following is a glossary of terms that will appear in this application:

[0038] Memory medium - any of various types of non-transitory memory devices or storage devices. The term "memory medium" is intended to include installation media, for example, CD-ROM, floppy disk or tape device; computer system memory or random access memory such as DRAM, DDR RAM, SRAM, EDO RAM, Rambus RAM, etc.; non-volatile memory such as flash memory, magnetic media, for example, hard disk drive or optical storage device; registers or other similar types of memory elements, etc. The memory medium may also include other types of non-transitory memory or their combination. In addition, the memory medium may be located in the first computer system executing the program, or may be located in a different second computer system connected to the first computer system via a network such as the Internet. In the latter example, the second computer system may provide program instructions to the first computer system for execution. The term "memory medium" may include two or more memory media that may reside in different locations in different computer systems connected, for example, via a network. The memory medium may store program instructions (e.g., expressed as a computer program) that may be executed by one or more processors.

[0039] Carrier Medium—storage media as described above, and physical transmission media such as a bus, network, and / or other physical transmission media that transport signals such as electrical, electromagnetic or digital signals.

[0040] Computer system (or computer)—any of various types of computing or processing systems, including a personal computer system (PC), a mainframe computer system, a workstation, a network appliance, an Internet appliance, a personal digital assistant (PDA), a television system, a grid computing system, or other devices or combinations of devices. In general, the term "computer system" may be broadly defined as any device (or combination of devices) that includes at least one processor that executes instructions from a memory medium.

[0041] User Equipment (UE) (or "UE device") - any of various types of computer systems or devices that are mobile or portable and that perform wireless communications. Examples of UE devices include mobile phones or smartphones (e.g., iPhones). TM , based on Android TM phones), tablets (e.g., iPad TM 、Samsung Galaxy TM ), portable gaming devices (e.g., Nintendo DS TM , PlayStation Portable TM 、Gameboy Advance TM , iPhone TM ), wearable devices (e.g., smart watches, smart glasses), laptops, PDAs, portable Internet devices, music players, data storage devices or other handheld devices, etc. In general, the term "UE" or "UE device" can be broadly defined to include any electronic device, computing device and / or telecommunication device (or combination of devices) that is convenient for a user to transport and capable of wireless communication.

[0042] Wireless Device—Any of various types of computer systems or devices that perform wireless communications. A wireless device may be portable (or mobile), or may be fixed or fixed at a location. A UE is an example of a wireless device.

[0043] Communication device - any of various types of computer systems or devices that perform communication, where the communication may be wired or wireless. A communication device may be portable (or mobile), or may be fixed or fixed at a location. A wireless device is one example of a communication device. A UE is another example of a communication device.

[0044] Base Station (BS)—The term “base station” has the full breadth of its ordinary meaning and includes at least a wireless communication station that is installed at a fixed location and used to communicate as part of a wireless telephone system or radio system.

[0045] Processing element (or processor) - refers to various elements or combinations of elements that are capable of performing functions in a device (e.g., a user equipment device or a cellular network device). A processing element may include, for example, a processor and associated memory, portions or circuits of various processor cores, an entire processor core, a single processor, an array of processors, circuits such as ASICs (application specific integrated circuits), programmable hardware elements such as field programmable gate arrays (FPGAs), and any of the above various combinations.

[0046] Wi-Fi—The term "Wi-Fi" has the full scope of its ordinary meaning and includes at least wireless communication networks or RATs that are served by wireless LAN (WLAN) access points and provide connectivity to the Internet through these access points. Most modern Wi-Fi networks (or WLAN networks) are based on the IEEE 802.11 standard and are marketed under the name "Wi-Fi". Wi-Fi (WLAN) networks are distinct from cellular networks.

[0047] Automatic—refers to an action or operation performed by a computer system (e.g., software executed by a computer system) or a device (e.g., a circuit, a programmable hardware element, an ASIC, etc.) without the need for user input to directly specify or perform the action or operation. Thus, the term "automatic" is contrasted with a user manually performing or specifying an action, where the user provides input to directly perform the action. An automatic process may be initiated by input provided by a user, but subsequent actions performed "automatically" are not specified by the user, i.e., are not performed "manually," where the user specifies each action to be performed. For example, a user filling out an electronic form by selecting each field and providing input specifying information (e.g., by typing in information, selecting check boxes, radio selections, etc.) is manually filling out the form, even though the computer system must update the form in response to the user action. The form may be automatically filled out by a computer system, where the computer system (e.g., software executed on the computer system) analyzes the fields of the form and fills out the form without any user input specifying the answers to the fields. As indicated above, a user may invoke automatic filling out of a form, but not participate in the actual filling out of the form (e.g., the user does not manually specify the answers to the fields but rather they are automatically completed). This specification provides various examples of operations that are automatically performed in response to actions taken by a user.

[0048] Configured to - Various components may be described as being "configured to" perform one or more tasks. In such environments, "configured to" is a broad statement that generally means "having a structure" that performs one or more tasks during operation. Thus, the component can be configured to perform the task even when the component is not currently performing the task (e.g., a set of electrical conductors can be configured to electrically connect a module to another module even when the two modules are not connected). In some environments, "configured to" can be a broad statement that generally means "having a circuit" that performs one or more tasks during operation. Thus, the component can be configured to perform the task even when the component is not currently turned on. Typically, the circuitry that forms the structure corresponding to "configured to" may include hardware circuitry.

[0049] For ease of description, various components may be described as performing one or more tasks. Such descriptions should be interpreted as including the phrase "configured to". The statement that a component is configured to perform one or more tasks is expressly intended not to invoke the interpretation of the sixth paragraph of 35 USC § 112 for that component.

[0050] Figure 1 and Figure 2 —Exemplary Communication System

[0051] Figure 1 An exemplary (and simplified) wireless communication system is shown that can implement various aspects of the present disclosure according to some embodiments. Note that Figure 1 The system is only one example of a possible system, and the embodiments may be implemented in any of a variety of systems as desired.

[0052] As shown, such an exemplary wireless communication system includes a base station 102, which communicates with one or more (e.g., any number) user equipment 106A, 106B, etc. 106N via a transmission medium. Each user equipment may be referred to herein as a "user device" (UE) or UE device. Therefore, user equipment 106 is referred to as a UE or UE device.

[0053] The base station 102 may be a base transceiver station (BTS) or a cell site, and may include hardware and / or software that implements wireless communications with UEs 106A to 106N. If the base station 102 is implemented in the context of LTE, it may be referred to as an "eNodeB" or "eNB". If the base station 102 is implemented in the context of 5G NR, it may alternatively be referred to as a "gNodeB" or "gNB". The base station 102 may also be equipped to communicate with a network 100 (e.g., a core network of a cellular service provider, a telecommunications network such as a public switched telephone network (PSTN), and / or the Internet, as well as various possibilities). Thus, the base station 102 may facilitate communications between user devices and / or between user devices and the network 100. The communication area (or coverage area) of a base station may be referred to as a "cell". Also as used herein, with respect to a UE, sometimes a base station may be considered to represent a network in consideration of the uplink and downlink communications of the UE. Therefore, a UE that communicates with one or more base stations in a network may also be interpreted as a UE that communicates with a network.

[0054] The base station 102 and the user equipment may be configured to communicate over a transmission medium using any of a variety of radio access technologies (RATs), also referred to as wireless communication technologies or telecommunication standards, such as GSM, UMTS (WCDMA, TD-SCDMA), LTE, Advanced LTE (LTE-A), LAA / LTE-U, 5G NR, 3GPP2, CDMA2000 (e.g., 1xRTT, 1xEV-DO, HRPD, eHRPD), Wi-Fi, etc.

[0055] Base station 102 and other similar base stations operating according to the same or different cellular communication standards may thus be provided as one or more cell networks that may provide continuous or nearly continuous overlapping service to UE 106 and similar devices over a geographic area via one or more cellular communication standards.

[0056] Note that UE 106 may be capable of communicating using multiple wireless communication standards. For example, UE 106 may be configured to communicate using either or both of the 3GPP cellular communication standard or the 3GPP2 cellular communication standard. In some embodiments, UE 106 may be configured to perform continuous conditional handover at least according to the various methods described herein. UE 106 may also or alternatively be configured to use WLAN, BLUETOOTH, or both. TM, one or more global navigation satellite systems (GNSS, such as GPS or GLONASS), one and / or more mobile television broadcast standards (e.g., ATSC-M / H or DVB-H), etc. Other combinations of wireless communication standards (including more than two wireless communication standards) are also possible.

[0057] Figure 2 An exemplary user device 106 (e.g., one of devices 106A to 106N) communicating with a base station 102 according to some embodiments is shown. UE 106 may be a device with wireless network connectivity, such as a mobile phone, a handheld device, a wearable device, a media player, a computer, a laptop, a tablet computer, or substantially any type of wireless device. UE 106 may include a processor (processing element) configured to execute process instructions stored in a memory. UE 106 may execute any of the method embodiments described herein by executing such stored instructions. Alternatively or in addition, UE 106 may include a programmable hardware element, such as an FPGA (field programmable gate array), an integrated circuit, and / or any of various other possible hardware components configured to execute (e.g., individually or in combination) any of the method embodiments described herein or any of any of the method embodiments described herein. UE 106 may be configured to communicate using any of a plurality of wireless communication protocols. For example, UE 106 may be configured to communicate using two or more of CDMA 2000, LTE, LTE-A, 5G NR, WLAN, or GNSS. Other combinations of wireless communication standards are also possible.

[0058] UE 106 may include one or more antennas for communicating according to one or more RAT standards using one or more wireless communication protocols. In some embodiments, UE 106 may share one or more parts of a receive chain and / or a transmit chain between multiple wireless communication standards. The shared radio component may include a single antenna, or may include multiple antennas for performing wireless communication (e.g., for MIMO). Typically, the radio component may include any combination of a baseband processor, an analog RF signal processing circuit (e.g., including filters, mixers, oscillators, amplifiers, etc.) and / or a digital processing circuit (e.g., for digital modulation and other digital processing). Similarly, the radio component may use the aforementioned hardware to implement one or more receive chains and transmit chains.

[0059] In some embodiments, UE 106 may include a separate transmit chain and / or receive chain (e.g., including separate antennas and other radio components) for each wireless communication protocol with which it is configured to communicate. As another possibility, UE 106 may include one or more radio components shared between multiple wireless communication protocols, and one or more radio components used uniquely by a single wireless communication protocol. For example, UE 106 may include a shared radio component for communicating using any of LTE or CDMA2000 1xRTT (or LTE or GSM, etc.), and a shared radio component for communicating using Wi-Fi and BLUETOOTH. TM Each of the independent radio components for communication. Other configurations are also possible.

[0060] Figure 3 —Block diagram of an exemplary UE device

[0061] Figure 3 A block diagram of an exemplary UE 106 according to some embodiments is shown. As shown, the UE 106 may include a system on a chip (SOC) 300, which may include parts for various purposes. For example, as shown, the SOC 300 may include one or more processors 302 that may execute program instructions for the UE 106, and a display circuit 304 that may perform graphics processing and provide display signals to a display 360. The SOC 300 may also include a motion sensing circuit 370, which may detect the motion of the UE 106, for example, using any of a gyroscope, an accelerometer, and / or various other motion sensing components. The one or more processors 302 may also be coupled to a memory management unit (MMU) 340, which may be configured to receive addresses from the one or more processors 302 and translate those addresses into locations in memory (e.g., memory 306, read-only memory (ROM) 350, NAND flash memory 310) and / or other circuits or devices, such as display circuit 304, radio 330, connector I / F 320, and / or display 360. The MMU 340 may be configured to perform memory protection and page table translation or setup. In some embodiments, the MMU 340 may be included as part of the one or more processors 302.

[0062] As shown, SOC 300 may be coupled to various other circuits of UE 106. For example, UE 106 may include various types of memory (e.g., including NAND flash memory 310), a connector interface 320 (e.g., for coupling to a computer system), a display 360, and wireless communication circuitry 330 (e.g., for LTE, LTE-A, NR, CDMA2000, BLUETOOTH TM, Wi-Fi, GPS, etc.). The UE device 106 may include at least one antenna (e.g., 335a), and may include multiple antennas (e.g., as shown by antennas 335a and 335b) for performing wireless communications with base stations and / or other devices. Antennas 335a and 335b are shown by way of example, and the UE device 106 may include fewer or more antennas. In general, one or more antennas are collectively referred to as antennas 335. For example, the UE device 106 may use antenna 335 to perform wireless communications with the aid of radio circuitry 330. As described above, in some embodiments, the UE may be configured to perform wireless communications using multiple wireless communication standards.

[0063] As further described later herein, the UE 106 (and / or the base station 102) may include hardware components and software components for implementing the method for at least the UE 106 to perform continuous conditional switching. The one or more processors 302 of the UE device 106 may be configured to implement part or all of the methods described herein, for example, by executing program instructions stored on a memory medium (e.g., a non-transitory computer-readable memory medium). In other embodiments, the one or more processors 302 may be configured as a programmable hardware element, such as an FPGA (field programmable gate array) or as an ASIC (application-specific integrated circuit). In addition, the one or more processors 302 may be coupled to a processor such as a processor 106. Figure 3 Other components are shown and / or may interoperate with other components to perform continuous conditional handover according to various embodiments disclosed herein. The one or more processors 302 may also implement various other applications and / or end-user applications running on the UE 106.

[0064] In some embodiments, radio 330 may include a separate controller dedicated to controlling communications for each respective RAT standard. Figure 3 As shown, the radio component 330 may include a Wi-Fi controller 350, a cellular controller (eg, an NR controller) 352, and a BLUETOOTH TM Controller 354, and in at least some embodiments, one or more or all of these controllers may be implemented as respective integrated circuits (referred to as ICs or chips) that communicate with each other and with SOC 300 (more specifically, with one or more processors 302). For example, Wi-Fi controller 350 may communicate with cellular controller 352 via a cell-ISM link or WCI interface, and / or BLUETOOTH TMController 354 may communicate with cellular controller 352 via a cell-ISM link, etc. Although three separate controllers are shown within radio 330, other embodiments may be implemented in UE device 106 having fewer or more similar controllers for various different RATs.

[0065] Additionally, embodiments are contemplated in which the controller may implement functionality associated with multiple radio access technologies. For example, according to some embodiments, in addition to hardware components and / or software components for performing cellular communications, the cellular controller 352 may include hardware components and / or software components for performing Wi-Fi preamble detection (e.g., for detecting a Wi-Fi physical layer preamble transmitted in an unlicensed band that may be associated with possible communications conducted by the UE 106 in an unlicensed spectrum). As another possibility, the cellular controller 352 may include hardware components and / or software components for generating a Wi-Fi physical layer preamble signal (e.g., for transmission as part of an uplink communication conducted by the UE 106 and occurring in an unlicensed band).

[0066] Figure 4 —Block diagram of an exemplary base station

[0067] Figure 4 1 shows a block diagram of an exemplary base station 102 according to some embodiments. Note that Figure 4 The base station of is only one example of a possible base station. As shown, the base station 102 may include one or more processors 404 that may execute program instructions for the base station 102. The one or more processors 404 may also be coupled to a memory management unit (MMU) 440 (which may be configured to receive addresses from the one or more processors 404 and convert these addresses to locations in memory (e.g., memory 460 and read-only memory (ROM) 450)) or to other circuits or devices.

[0068] Base station 102 may include at least one network port 470. Network port 470 may be configured to couple to a telephone network and provide access to the telephone network described above. Figure 1 and Figure 2The network port 470 may be coupled to a telephone network as described in the foregoing, such as a UE device 106. The network port 470 (or an additional network port) may be further configured or alternatively configured to be coupled to a cellular network, such as a core network of a cellular service provider. The core network may provide mobility-related services and / or other services to multiple devices such as the UE device 106. For example, the core network may include a mobility management entity (MME), for example, for providing mobility management services, a serving gateway (SGW) and / or a packet data network gateway (PGW), for example, for providing external data connections, such as connections to the Internet, etc. Other configurations are also possible. In some cases, the network port 470 may be coupled to a telephone network via the core network, and / or the core network may provide a telephone network (e.g., in a UE device served by a cellular service provider).

[0069] The base station 102 may include at least one antenna 434 and possibly multiple antennas. One or more antennas 434 may be configured to operate as a wireless transceiver and may also be configured to communicate with the UE device 106 via the radio component 430. One or more antennas 434 communicate with the radio component 430 via a communication chain 432. The communication chain 432 may be a receiving chain, a transmission chain, or both. The radio component 430 may be designed to communicate via various wireless telecommunication standards, including but not limited to NR, LTE, LTE-A GSM, UMTS, CDMA2000, Wi-Fi, etc. The processor 404 of the base station 102 may be configured to implement and / or support implementation of part or all of the methods described herein, for example, by executing program instructions stored on a memory medium (e.g., a non-transitory computer-readable memory medium). Alternatively, the processor 404 may be configured as a programmable hardware element such as an FPGA (field programmable gate array), or as an ASIC (application-specific integrated circuit) or a combination thereof. In the case of certain RATs (e.g., Wi-Fi), the base station 102 may be designed as an access point (AP), in which case the network port 470 may be implemented to provide access to a wide area network and / or one or more local area networks, for example, it may include at least one Ethernet port, and the radio component 430 may be designed to communicate according to the Wi-Fi standard. The base station 102 may operate according to various methods disclosed herein for enabling a wireless device to perform continuous conditional handover.

[0070] Figure 5 —Continuous conditional switching

[0071] Wireless devices operating in a radio resource control (RRC) connected mode may have their mobility operations managed by the cellular network with which they are registered, such as through handover operations. In some cases, such handovers may include a serving base station providing signaling to the wireless device that configures (e.g., periodically or in an event-based manner) the wireless device to perform measurements on neighboring cells, receiving signaling including measurement reports from the wireless device based on those measurements, and providing signaling to the wireless device to configure a handover to another cell if certain handover conditions are met.

[0072] Using such timely signaling between the network and the device to perform handovers can allow for dynamic selection of the best cell to perform the handover when a handover is required. However, such timely signaling can sometimes cause handover failures, for example, because timely configured handovers can often occur under relatively weak channel / signal conditions. These situations may be more common under fast moving conditions, in high cell density deployments in frequency ranges with high propagation losses that utilize directional transmissions (beamforming), and / or more generally in scenarios where channel quality may degrade relatively quickly, at least according to some embodiments.

[0073] Thus, in some cases, conditional handover can be used, for example, to reduce reliance on timely RRC signaling from the source cell at the time of handover, which can make the handover more reliable. Conditional handover can include attempting to pre-deliver a handover command for a cell in advance, for example, when conditions are good (e.g., when the device is stationary and / or has good signal quality), and allowing the device to handover later, for example, with a reduced set of signaling. These techniques can help reduce data loss, gaps, and pauses, and can help reduce latency for a wireless device to handover from one cell to another.

[0074] In some cases, it may be more useful to provide conditional handover information that supports multiple (e.g., consecutive) conditional handovers. For example, it may be the case that providing conditional handover information that can support multiple consecutive conditional handovers can reduce the likelihood of a handover failure occurring after a conditional handover is performed due to a brief stay on the target cell of the conditional handover before wireless medium conditions degrade and further handovers are required. Therefore, Figure 5 is a signal flow diagram illustrating an exemplary possible method for performing continuous conditional switching according to some embodiments.

[0075] Figure 5Aspects of the methods of the present invention may be implemented by a cellular base station (such as the BS 102 shown and described with respect to the various figures herein) and a wireless device (such as the UE 106 shown and described with respect to the various figures herein), or more generally, as desired, in conjunction with any of the computer circuits, systems, devices, elements or components, etc. shown in the above figures. For example, a processor (and / or other hardware) of such a device may be configured to cause the device to perform any combination of the method elements shown and / or other method elements.

[0076] It is noted that although the present invention is described in a manner involving the use of communication techniques and / or features associated with LTE, NR and / or 3GPP specification documents, Figure 5 At least some elements of the method, but this description is not intended to limit the present disclosure and can be used in any suitable wireless communication system as needed Figure 5 In various embodiments, some of the method elements shown may be performed simultaneously in an order different from that shown, may be replaced by other method elements, or may be omitted. Additional method elements may also be performed as needed. As shown in the figure, Figure 5 The method can be operated as follows.

[0077] At 512, a first cellular base station 502 (e.g., providing a first cell) may provide a conditional handover request to a second cellular base station 504 (e.g., providing a second cell). The first cellular base station 502 may provide the conditional handover request based on determining to provide conditional handover information (e.g., including a conditional handover command) to a wireless device 506 served by the first cell. The first cellular base station 502, as well as the second cellular base station 504, the cellular base station 508, and possibly a plurality of other cellular base stations, may provide a radio access network that provides an air interface between a cellular core network and a wireless device 506 (e.g., and / or other wireless devices served by a cellular network), at least according to some embodiments.

[0078] The conditional handover request may indicate a set of candidate cells to include conditional handover information. For example, the set of candidate cells may include the first cell, the second cell, and a third cell provided by the third cellular base station 508. According to various embodiments, the cells may be identified by cell frequency (such as an E-UTRA absolute radio frequency channel number in an LTE environment), a physical cell identifier, and a global cell identifier, and / or in any of a variety of other ways.

[0079] In 514, the second cellular base station 504 may respond to the conditional handover request. The response may include any of a variety of possible types of information. As one possibility, the response may include configuration information for the second cell, for example, for the wireless device 506 to determine the configuration used when sending a handover confirmation to the second cell and / or otherwise communicating with the second cell. The configuration information may be provided as complete configuration information, or in an incremental format, for example, indicating a change in the configuration for the second cell relative to the configuration information for the first cell. As another possibility, the response may include information for performing a conditional handover from the second cell to each candidate cell indicated in the conditional handover request (e.g., the first cell and the third cell according to the aforementioned example).

[0080] Note that the first cellular base station 502 may similarly provide a conditional handover request to any other cellular base station providing cells in the set of candidate cells. Thus, again in accordance with the aforementioned example, it may be the case that the cellular base station also provides a conditional handover request to the third cellular base station 508, which request may similarly indicate a set of candidate cells for which conditional handover information is to be included. Thus, in this scenario, the third cellular base station 508 may similarly respond with configuration information for the third cell and information for performing a conditional handover from the second cell to each candidate cell indicated in the conditional handover request. Any other cellular base station provided with a conditional handover request may also respond and include in the response similar information for one or more cells provided by one or more cellular base stations.

[0081] In 516, the first cellular base station 502 may provide conditional handover information (e.g., including a conditional handover command) to the wireless device 506. The conditional handover information may support continuous conditional handover by the wireless device 506. For example, the conditional handover information may include information for performing a conditional handover from a first cell to one or more other cells, and information for performing a conditional handover from at least one of those other cells to at least another other cell. As one such possibility, consider again a scenario in which conditional handover information for a group of cells including a first cell, a second cell, and a third cell is provided, and the conditional handover information may include information for performing a conditional handover from the first cell to the second cell and the third cell, information for performing a conditional handover from the second cell to the third cell and the first cell, and information for performing a conditional handover from the third cell to the second cell and the first cell.

[0082] The conditional handover information may also include configuration information for one or more cells. For example, as one possibility, the conditional handover information may include configuration information for each cell in the group of cells for which the conditional handover information is provided, except for the first cell (e.g., because the wireless device 506 may already have configuration information for the first cell, since the first cell may be the current serving cell 506 for the wireless device). Therefore, again considering the case where conditional handover information is provided for a group of cells including the first cell, the second cell, and the third cell, the conditional handover information may include configuration information for the second cell and the third cell.

[0083] Note that in some cases, the conditional handoff information may be provided in a single conditional handoff command or in multiple conditional handoff commands to the wireless device 506. For example, as one possibility, the first base station 502 may wait until it has received responses to all conditional handoff requests it has provided, and then provide conditional handoff information in a single conditional handoff command for all cells whose conditional handoff information is provided to the wireless device 506. As another possibility, once the first base station 502 has received responses to conditional handoff requests from base stations providing the corresponding cells, the first base station 502 may provide conditional handoff information for each corresponding cell in its own conditional handoff command, and the conditional handoff information for those corresponding cells is provided to the wireless device 506.

[0084] The information for performing conditional switching from a first cell to a second cell may specify one or more conditions required for conditional switching from the first cell to the second cell. Similarly, the information for performing conditional switching from the second cell to the third cell may specify one or more conditions required for conditional switching from the second cell to the third cell. More generally, the information for performing conditional switching from one cell to another cell may specify one or more conditions required for conditional switching from one cell to another cell. These conditions may include threshold information indicating one or more threshold conditions to be met for conditional switching. The threshold / condition may include a service / source cell signal strength (e.g., RSRP) and / or signal quality (e.g., RSRQ) threshold, a candidate / target cell signal strength and / or signal quality threshold, an incremental signal strength and / or signal quality threshold between a service / source cell and a candidate / target cell, and / or any of a variety of other possible conditions. In some cases, one or more conditions may include an A3 trigger and / or an A5 trigger, for example, according to a 3GPP specification document. Note that each potential conditional switch may have a different threshold / condition, or some or all potential conditional switches may have similar or identical thresholds / conditions for performing the conditional switch.

[0085] Note that, at least in some cases, the wireless device 506 may provide capability information to the network (e.g., to the first cellular base station 502 or a previous serving cell) that indicates whether the wireless device 506 is capable of supporting conditional handover, whether the wireless device 506 is capable of supporting continuous conditional handover, and / or how much conditional handover information the wireless device 506 can support. For example, since storing conditional handover information for a set of cells may require a greater amount of storage capacity for a larger set of cells, the capability information may include an indication of the maximum amount of conditional handover information supported by the wireless device, such as by indicating a maximum cell set size (e.g., a maximum number of candidate cells) supported by the wireless device, and / or using any of a variety of other possible metrics or indicators. In such a scenario, the first cellular base station may determine to provide conditional handover information to the wireless device 506 based at least in part on the capability information of the wireless device 506, possibly including selecting a set of cells for which to provide conditional handover information, and / or determining any of a variety of other possible aspects of the conditional handover information based at least in part on the capability information.

[0086] In 518, the wireless device 506 may perform a conditional handover using the conditional handover information received from the first cellular base station 502. For example, if a threshold condition for performing a conditional handover from the first cell to the second cell is met while the wireless device 506 is connected to the first cell, the wireless device 506 may perform a conditional handover from the first cell to the second cell using the conditional handover information. In this case, the wireless device 506 may send a handover confirmation to the second cell (i.e., the cell to which the handover is being performed). It is noted that it may be the case that, at least in some cases, performing a conditional handover may not require or include any additional signaling between the wireless device 506 and the previous serving cell (i.e., the first cell from which the handover is being performed) after the conditional handover is met. This may help reduce the likelihood of a handover failure, for example, due to the fact that the previous serving cell may have become relatively weak at that time and the chance of such signaling being unsuccessful may be correspondingly relatively high.

[0087] According to at least some embodiments, the wireless device 506 can retain the conditional handoff information received from the first cellular base station 502 after performing the conditional handoff. Thus, if the conditions for one or more additional conditional handoffs are met, the wireless device 506 can use the stored conditional handoff information to perform one or more additional conditional handoffs using the same conditional handoff information. In other words, the wireless device 506 can perform multiple consecutive conditional handoffs using the conditional handoff information provided to the wireless device 506, for example, without any additional handoff commands from the network.

[0088] For example, as shown, in 520, the wireless device 506 may also perform conditional handover using conditional handover information received from the first cellular base station 502. As shown, if a threshold condition for performing conditional handover from the second cell to the third cell is met while the wireless device 506 is connected to the second cell, the wireless device 506 may also perform conditional handover from the second cell to the third cell using the conditional handover information. At least according to some embodiments, if the condition of the conditional handover information is met, such conditional handover according to the conditional handover information may continue to be performed, or alternatively until one or more other events that trigger cancellation or modification of the conditional handover information occur.

[0089] There may be any number of reasons / reasons for discarding / canceling the conditional handover information. As one possibility, the serving cell of the wireless device 506 may provide an indication to discard / release the conditional handover information currently stored by the wireless device 506. Similarly, the serving cell of the wireless device 506 may provide updated conditional handover information to the wireless device 506, which may implicitly supersede and thus cancel any conditional handover information previously provided to the wireless device 506, or may include an explicit indication to discard / release any previously provided conditional handover information in conjunction with the updated conditional handover information. As another possibility, the serving cell of the wireless device 506 may configure a handover for the wireless device 506 (e.g., provide a handover command) that includes an indication to discard / release the conditional handover information currently stored by the wireless device 506, in which case the wireless device 506 may perform the handover and release the conditional handover information in accordance with the handover command. It should be noted that the serving cell of the wireless device may also configure the handover of the wireless device 506 (e.g., provide a handover command) that includes an instruction to maintain the conditional handover information currently stored by the wireless device 506. In this case, the wireless device 506 may perform the handover according to the handover command and continue to retain the conditional handover information. In such a scenario, the wireless device 506 may perform a conditional handover using the stored conditional handover information at one or more subsequent occasions.

[0090] According to at least some embodiments, the conditional handover information may be associated with a single RRC connection. Thus, as another possibility, at least in some cases, if the RRC connection of the wireless device 506 is released, the wireless device 506 may discard the conditional handover information. Similarly, if the wireless device 506 detects a radio link failure and is unable to recover from the radio link failure on the same cell where the radio link failure occurred, the wireless device 506 may discard the conditional handover information.

[0091] It should be noted that although there may be situations where a different cellular base station provides each cell for which conditional handover information is provided to the wireless device 506, as in the illustrated examples of the first base station 502 and the first cell, the second base station 504 and the second cell, and the third base station 508 and the third cell, such scenarios should not be considered to limit the present disclosure as a whole. For example, there may also or alternatively be situations where a base station can provide multiple cells so that conditional handover information can be provided for those multiple cells by the same base station. In such a scenario, a conditional handover request for multiple cells provided by the base station can be provided to the base station, and the response can include conditional handover information for those multiple cells. Similarly, the wireless device can perform a conditional handover from one cell provided by the base station to another cell provided by the same base station, for example, if the conditions for the conditional handover are met.

[0092] It should also be noted that in addition to or alternatively to performing continuous conditional switching of the primary cell or the serving cell, Figure 5 The described techniques may be used with secondary cell changes. For example, at least according to some embodiments, in a system supporting carrier aggregation and / or dual connectivity, a wireless device may be configured to perform a continuous conditional secondary cell group (SCG) change using the conditional handover information provision techniques described herein.

[0093] Therefore, using the techniques described herein, the network can configure the wireless device to perform continuous conditional handover and enable the wireless device to perform continuous conditional handover. At least in some cases, such techniques can improve the robustness of handovers in cellular networks, such as in at least some high cell density deployment scenarios among various possibilities.

[0094] Figures 6 to 16 and additional information

[0095] Provided Figures 6 to 16 and the following information, which illustrates the Figure 5 The present invention provides further considerations and possible implementation details of the method, and is not intended to limit the present disclosure as a whole. Various changes and alternatives to the details provided below are possible and should be considered to fall within the scope of the present disclosure.

[0096] Conditional handover techniques may be used to improve handover robustness in cellular communication systems such as 3GPP 5G NR. These techniques may include a cellular base station providing a handover command in advance to reduce or avoid the possibility of a traditional handover failure due to a measurement result transmission failure or a handover command transmission failure.

[0097] For example, Figure 6606, UE 602 may trigger an A3 event (e.g., a neighboring cell may have a better signal strength than a primary cell of UE 602. In 608, UE 602 may attempt to send a measurement report to a source node 604 providing a primary cell, but source node 604 may not receive the measurement report. In 610, the wireless medium condition between UE 602 and source node 604 may become worse, UE 602 may declare a radio link failure, and may initiate radio resource control reconstruction. Specifically, UE 602 may send a reconstruction request in 612, receive a reconstruction message in 614, send a reconstruction completion message in 616, and receive a reconfiguration message in 618.

[0098] Another example: Figure 7 706, UE 702 may trigger an A3 event (e.g., a neighboring cell may have a better signal strength than a primary cell of UE 702). In 708, UE 702 may send a measurement report to a source node 704 providing a primary cell, which may be received by source node 704. In 710, source node 704 may attempt to send a handover command to UE 702, but UE 702 may not receive the handover command. In 712, the wireless medium condition between UE 702 and source node 704 may become worse, UE 702 may declare a radio link failure, and may initiate radio resource control reconstruction. Specifically, UE 702 may send a reconstruction request in 714, receive a reconstruction message in 716, send a reconstruction completion message in 718, and receive a reconfiguration message in 720.

[0099] In contrast, Figure 8It is a signal flow chart showing various aspects of the scene that conditional handover command is used to avoid these potential handover failure scenes.As shown in the figure, in 808, the source node can provide conditional handover request to potential target node 806.In 810, the potential target node can provide conditional handover request confirmation (for example, including RRCR configuration information for potential target node 806) to source node 804.It should be noted that multiple such conditional handover requests can be provided to multiple potential target nodes, for example, to support the conditional handover information for multiple potential conditional handover target cells provided to UE.In 812, the source node 804 can provide conditional handover configuration information (for example, including conditional information for triggering conditional handover, such as A3 / A5 event, RRCRe configuration information for potential target node 806, and possible similar information for one or more other potential target cells) to UE 802.In 814, UE 802 can monitor the conditional handover conditions of one or more target cells.In 816, if the condition of conditional handover is met, UE 802 can perform handover. In the illustrated scenario, this may include performing random access and synchronization in 818, and receiving an RRCReconfigurationComplete message in 820. Once the handover is complete, the potential target node (now the serving cell) 806 may perform path switching and UE context release for the UE in the network. The UE 802 may also release configuration information for all conditional handover candidates after any (e.g., conditional or legacy) successful handover is completed.

[0100] In some frequency ranges, such as NR FR2 deployments, there may be situations where relatively high cell density is provided and rapidly varying signal strengths (e.g., RSRP) may be common, for example due to the use of directional antennas, which may potentially result in a relatively large number of handovers and radio link failures for wireless devices operating in these frequency ranges. As a result, it may be a relatively common scenario where conventional handover failures may occur, such as in Figure 6 to Figure 7 In the scene shown. Fig. 9Further details of such a scenario are shown, where a conventional handover failure may occur, for example, in a frequency range with the possibility of rapidly changing wireless medium conditions. As shown, in the illustrated scenario, the UE 902 may provide a measurement report (e.g., due to an A3 trigger, as one possibility) and receive a handover command from a first cell 904 of the network. The UE 902 may provide a handover completion message to a second cell 906 (e.g., the target of the handover command), and may attempt to provide a measurement report to the second cell 906 (e.g., due to another A3 trigger, as one possibility). However, due to the rapid deterioration of conditions on the second cell 906, the second cell 906 may not receive the measurement report from the UE 902, which may result in a handover failure and potential radio link failure. Therefore, instead of completing the handover to the third cell 908 or any other cell, a service interruption may occur.

[0101] Under such fast changing conditions with high cell density, it may be the case that even configuring conditional handover may not be sufficient to prevent eventual handover failure and possible radio link failure. Fig.10 Further details of this scenario in which a conditional handover failure may occur are shown. As shown, in the illustrated scenario, the UE 1002 may provide a measurement report and receive a conditional handover command from the first cell 1004 of the network. The UE 1002 may determine that the conditions for handover to the second cell 1006 are met, and the handover may be performed, including providing a conditional handover completion message to the second cell 1006, and may attempt to provide a measurement report to the second cell 1006. However, due to the rapid deterioration of conditions on the second cell 1006, the second cell 1006 may not receive the measurement report from the UE 1002, which may result in a handover failure and potential radio link failure. Therefore, instead of receiving a conditional handover command and completing a handover to the third cell 908 or any other cell, a service interruption may occur.

[0102] Therefore, it is possible that service interruption may occur due to a short stay on a cell, which causes the wireless device to be unable to send measurement reports and / or handover-related messages in a timely manner and causes handover failure and radio link failure. One possible approach to attempt to mitigate the possibility of such service interruption may include extending the conditional handover framework to support the possibility of configuring multiple (e.g., consecutive) conditional handovers.

[0103] In order to support the possibility of configuring continuous conditional handover according to the conditional handover command, a handover preparation operation can be performed on the network side. Such an operation may include each target node / cell providing the configuration of the candidate cell and one or more conditional handover conditions for performing conditional handover from the cell when the UE performs conditional handover in a candidate cell. The target node / cell may provide the configuration information of the candidate cell as complete configuration information or incremental configuration information. In the case of providing incremental configuration information, as a possibility, the increment may be relative to the current configuration of the source cell. At least in some cases, the network may also explicitly indicate to the UE to maintain the configuration information of the candidate cell after the handover is completed.

[0104] When the UE receives a conditional handover command with such a "keep" indication (e.g., indicating that the configuration information of the candidate cell is maintained after the handover is completed), the UE may store the complete configuration of each candidate cell and one or more conditional handover conditions. If the network provides the configuration of the candidate cell as incremental configuration information (e.g., instead of complete configuration information), it is possible that the UE converts and stores the configuration information of the candidate cell as complete configuration information. For conditional handover condition configuration for the candidate cell, the UE may store such information together with the configuration information of the candidate cell. For the first conditional handover performed according to the conditional handover command, the UE may use one or more conditional handover conditions configured via the current serving cell. Once the UE successfully performs conditional handover on a candidate cell, the UE may apply the configuration of the candidate cell, for example, including one or more conditional handover conditions configured for potentially performing conditional handover from the cell. After the UE handover is successfully completed, the UE may maintain the configuration information of all candidate cells, for example, for potentially performing further conditional handovers. In some cases, the UE (e.g., optionally) may remove the source cell from the candidate cell list. Note that, at least according to some embodiments, such a framework and process may be applicable to both primary cell (PCell) changes (handovers) as well as secondary cell (SCell) changes (secondary cell group (SCG) changes).

[0105] There may be a number of possible methods to perform network preparation to provide support for performing continuous conditional handovers. Fig.11One such possible method is shown, in which a single conditional handover command is used to configure a potential continuous conditional handover of multiple candidate cells. As shown, in the illustrated scenario, the UE 1102 may initially connect to the first cell 1104, for example, so that in 1110, the UE 1102 may have cell configuration information for the first cell 1104. The first cell 1104 may decide to trigger a conditional handover, and may send a conditional handover request to the second cell 1106 in 1112, and send the conditional handover request to the third cell 1108 in 1114. The conditional handover request may indicate a proposed candidate cell (e.g., the first cell 1104, the second cell 1106, and the third cell 1108) for potential further conditional handovers. In 1116, the second cell 1106 may provide a conditional handover request confirmation to the first cell 1104. The confirmation may include RRC reconfiguration information for the second cell 1106 and conditional handover conditions for performing handover from the second cell 1106 to the first cell 1104 and to the third cell 1108. In 1118, the third cell 1108 may provide a conditional handover request confirmation to the first cell 1104. The confirmation may include RRC reconfiguration information for the third cell 1108 and conditional handover conditions for performing handover from the third cell 1108 to the first cell 1104 and to the second cell 1106. In 1120, the first cell 1104 may provide a conditional handover command to the UE 1102. The conditional handover command may include one or more conditional handover conditions for performing conditional handover from the first cell 1104, configuration information for the second cell 1106 and one or more conditional handover conditions for performing conditional handover from the second cell 1106, and configuration information for the third cell 1108 and one or more conditional handover conditions for performing conditional handover from the third cell 1108. In 1122, when a conditional switching command is received from the first cell 1104, the UE 1102 can store complete configuration information for the second cell 1106 and the third cell 1108, as well as conditional switching conditions for performing conditional switching from each of the first cell 1104, the second cell 1106 and the third cell 1108.

[0106] Fig.12Another possible method of performing network preparation to provide support for performing continuous conditional handover is shown, wherein multiple conditional handover commands are used to configure potential continuous conditional handover of multiple candidate cells. As shown, in the illustrated scenario, UE 1202 may initially connect to first cell 1204, for example, so that UE 1202 may have cell configuration information for first cell 1204. First cell 1204 may decide to trigger conditional handover, and may send a conditional handover request to second cell 1206 in 1212, and send the conditional handover request to third cell 1208 in 1214. The conditional handover request may indicate a proposed candidate cell (e.g., first cell 1204, second cell 1206, and third cell 1208) for potential further conditional handover. In 1216, second cell 1206 may provide conditional handover request confirmation to first cell 1204. The confirmation may include RRC reconfiguration information for the second cell 1206 and conditional handover conditions for performing handover from the second cell 1206 to the first cell 1204 and to the third cell 1208. In 1218, the first cell 1204 may provide a first conditional handover command to the UE 1202. The first conditional handover command may include one or more conditional handover conditions for performing conditional handover from the first cell 1204 to the second cell 1206, as well as configuration information for the second cell 1206 and one or more conditional handover conditions for performing conditional handover from the second cell 1206. In 1220, upon receiving the first conditional handover command from the first cell 1204, the UE 1202 may store the complete configuration information for the second cell 1206, the conditional handover conditions for performing conditional handover from the first cell 1204 to the second cell 1206, and the conditional handover conditions for performing conditional handover from the second cell 1106. In 1222, the third cell 1208 may provide a conditional handover request confirmation to the first cell 1204. The confirmation may include RRC reconfiguration information for the third cell 1208 and conditional handover conditions for performing handover from the third cell 1208 to the first cell 1204 and to the second cell 1206. In 1224, the first cell 1204 may provide a second conditional handover command to the UE 1202. The second conditional handover command may include one or more conditional handover conditions for performing conditional handover from the first cell 1204 to the second cell 1208, as well as configuration information for the third cell 1208 and one or more conditional handover conditions for performing conditional handover from the third cell 1208.In 1226, when a second conditional switching command is received from the first cell 1204, the UE 1202 may store complete configuration information for the third cell 1208, as well as conditional switching conditions for performing conditional switching from the first cell 1204 to the third cell 1208, and conditional switching conditions for performing conditional switching from the third cell 1108.

[0107] Once the network preparation for supporting continuous conditional handover by the UE is completed (e.g., according to Fig.11 The scene shown, Fig.12 In the scenario shown, or any of a variety of other methods of performing such network preparation), the UE may be configured to perform continuous conditional handover. Fig.13 Further details of how such continuous conditional handover can be performed by the UE according to some embodiments are shown. In the scenario shown, the UE 1302 can initially be connected to the first cell 1304. The UE 1302 can provide a measurement report to the first cell 1304, which can provide a conditional handover command to configure possible continuous conditional handover with the second cell 1306 and the third cell 1308. The UE 1302 can store complete configuration information for the first cell 1304, the second cell 1306, and the third cell 1308, as well as conditional handover conditions for performing conditional handover from each of the first cell 1304, the second cell 1306, and the third cell 1308. When the UE 1302 remains connected to the first cell 1304, the UE can apply the conditional handover conditions for performing conditional handover from the first cell 1304 when evaluating the second cell 1306 and the third cell 1308. In the illustrated scenario, conditions for performing a conditional handover from a first cell 1304 to a second cell 1306 may be satisfied, and the UE 1302 may perform the handover to the second cell 1306, e.g., including providing a conditional handover complete message to the second cell 1306. After the handover to the second cell 1306 is completed, the UE 1302 may retain all configuration and conditional handover information, may apply the configuration information for the second cell 1306 based on data communications, may notify the second cell 1306 that the UE 1302 retains continuous conditional handover configuration information for the first cell 1304, the second cell 1306, and the third cell 1308, and may apply conditional handover conditions to evaluate the first cell 1304 and the third cell 1308. Note that in a framework where separate conditional handover commands are used to configure potential continuous conditional handovers to different cells, such as in Fig. 9In the scenario shown, if UE 1302 performs a conditional handover to the second cell 1306 before UE 1302 receives a conditional handover command including conditional handover configuration information for the third cell 1308, UE 1302 can instead notify the second cell 1306 that UE 1302 retains continuous conditional handover configuration information for the first cell 1304 and the second cell 1306 (but not the third cell 1308).

[0108] exist Fig.13 In the illustrated scenario, when connected to the second cell 1306, conditions for performing a conditional handover from the second cell 1306 to the third cell 1308 may be satisfied, and the UE 1302 may perform a handover to the third cell 1308, for example, including providing a conditional handover completion message to the third cell 1308. Likewise, after the handover to the third cell 1308 is completed, the UE 1302 may retain all configuration and conditional handover information, may apply the configuration information for the third cell 1308 according to the data communication, may notify the third cell 1308 that the UE 1302 retains continuous conditional handover configuration information for the first cell 1304, the second cell 1306, and the third cell 1308, and may apply the conditional handover conditions to evaluate the first cell 1304 and the second cell 1306. Note that at any time during such a scenario, at least according to some embodiments, the current conditional handover configuration of the UE 1302 may be overwritten by a new configuration of the network, and / or the current conditional handover configuration of the UE 1302 may be released by a network release indication.

[0109] Additionally, if an explicit handover command is provided to the UE while the UE has conditional handover configuration information, there may be multiple possibilities as to whether to continue to use the conditional handover configuration information. Figures 14 to 15 is a signal flow diagram illustrating aspects of an exemplary such scenario in which a handover command is provided to a wireless device that has been configured to perform continuous conditional handover according to some embodiments.

[0110] exist Fig.14In the scenario of FIG. 1404, UE 1402 may initially connect to first cell 1404, for example, so that in 1410, UE 1402 may have cell configuration information for first cell 1404. First cell 1404 may decide to trigger conditional handover, and may send a conditional handover request to second cell 1406 in 1412, and send the conditional handover request to third cell 1408 in 1414. The conditional handover request may indicate a proposed candidate cell for potential further conditional handover (e.g., first cell 1404, second cell 1406, and third cell 1408). In 1416, second cell 1406 may provide conditional handover request confirmation to first cell 1404. The confirmation may include RRC reconfiguration information for second cell 1406 and conditional handover conditions for performing handover from second cell 1406 to first cell 1404 and to third cell 1408. In 1418, the third cell 1408 may provide a conditional handover request confirmation to the first cell 1404. The confirmation may include RRC reconfiguration information for the third cell 1408 and conditional handover conditions for performing handover from the third cell 1408 to the first cell 1404 and to the second cell 1406. In 1420, the first cell 1404 may provide a conditional handover command to the UE 1402. The conditional handover command may include one or more conditional handover conditions for performing conditional handover from the first cell 1404, as well as configuration information for the second cell 1406 and one or more conditional handover conditions for performing conditional handover from the second cell 1406, and configuration information for the third cell 1408 and one or more conditional handover conditions for performing conditional handover from the third cell 1408. In 1422, upon receiving the conditional handover command from the first cell 1404, the UE 1402 may store complete configuration information for the second cell 1406 and the third cell 1408, and conditional handover conditions for performing conditional handover from each of the first cell 1404, the second cell 1406, and the third cell 1408. In 1424, the first cell 1404 may provide a handover command to the UE 1402, wherein the first cell 1404 instructs the UE 1402 to use the second cell 1404 as a handover target and releases the conditional handover information provided to the UE 1402. In 1426, the UE 1402 may release the conditional handover configuration information and comply with the handover command, for example, including providing a handover complete message to the second cell 1406 in 1428.

[0111] exist Fig.15In the scenario of FIG. 1504, UE 1502 may initially connect to first cell 1504, for example, so that in 1510, UE 1502 may have cell configuration information for first cell 1504. First cell 1504 may decide to trigger conditional handover, and may send a conditional handover request to second cell 1506 in 1512, and send the conditional handover request to third cell 1508 in 1514. The conditional handover request may indicate a proposed candidate cell for potential further conditional handover (e.g., first cell 1504, second cell 1506, and third cell 1508). In 1516, second cell 1506 may provide conditional handover request confirmation to first cell 1504. The confirmation may include RRC reconfiguration information for second cell 1506 and conditional handover conditions for performing handover from second cell 1506 to first cell 1504 and to third cell 1508. In 1518, the third cell 1508 may provide a conditional handover request confirmation to the first cell 1504. The confirmation may include RRC reconfiguration information for the third cell 1508 and conditional handover conditions for performing handover from the third cell 1508 to the first cell 1504 and to the second cell 1506. In 1520, the first cell 1504 may provide a conditional handover command to the UE 1502. The conditional handover command may include one or more conditional handover conditions for performing conditional handover from the first cell 1504, as well as configuration information for the second cell 1506 and one or more conditional handover conditions for performing conditional handover from the second cell 1506, and configuration information for the third cell 1508 and one or more conditional handover conditions for performing conditional handover from the third cell 1508. In 1522, upon receiving the conditional handover command from the first cell 1504, the UE 1502 may store complete configuration information for the second cell 1506 and the third cell 1508, and conditional handover conditions for performing conditional handover from each of the first cell 1504, the second cell 1506, and the third cell 1508. In 1524, the first cell 1504 may provide a handover command to the UE 1502, wherein the first cell 1504 instructs the UE 1502 to use the second cell 1504 as a handover target, and maintain the conditional handover information provided to the UE 1502. In 1526, the UE 1502 may maintain the conditional handover configuration information and comply with the handover command, for example, including providing a handover complete message to the second cell 1506 in 1528. In 1530 , UE 1502 may determine that conditions for triggering a conditional handover to third cell 1508 may be satisfied, and may therefore perform a conditional handover to third cell 1508 , including, for example, providing a handover complete message to third cell 1508 in 1532 .

[0112] Fig.16 1 is a signal flow diagram illustrating aspects of an exemplary possible scenario according to some embodiments, in which a wireless device provides information indicating whether the wireless device supports the capability of continuous conditional handover. As shown, in 1612, the network 1604 may provide a UE capability query to the UE 1602. The UE capability query may represent a request for the UE to provide any of various types of capability information, such as frequency band capabilities, whether the UE supports various functions, and / or any of various other types of information. One such possible type of information may include information about the conditional handover capability of the UE 1602.

[0113] In 1614, the UE 1602 may respond to the UE capability query by providing the requested UE capability information. This may include an indication of whether the UE 1602 supports conditional handover, whether the UE 1602 supports continuous conditional handover, whether the UE 1602 supports multiple conditional handover candidate cells, a maximum number of conditional handover candidate cells supported by the UE 1602, and / or any or all of any of a variety of other types of information.

[0114] In 1616, the network 1604 may provide a conditional handover command to the UE 1602. The network may determine to provide the conditional handover command, and / or may select certain aspects of the conditional handover information provided in the conditional handover command based at least in part on the UE capability information provided by the UE 1602. For example, if the UE capability information indicates that the UE 1602 can support conditional handover, the network may only provide the conditional handover command to the UE 1602. In addition, the number of cells for which the conditional handover information is provided may be selected to be less than or equal to the maximum number of conditional handover candidate cells supported by the UE 1602. According to various embodiments, the network 1604 may additionally or alternatively determine whether to provide the conditional handover command to the UE 1602 and / or what information about any of the various other possible types of capability information provided by the UE 1602 to include in the conditional handover command, and there are other possible considerations.

[0115] In the following, further exemplary embodiments are provided.

[0116] A set of embodiments may include an apparatus comprising: a processor configured to cause a wireless device to: receive conditional switching information from a first cellular base station, wherein the conditional switching information supports continuous conditional switching; perform a first conditional switching using the conditional switching information received from the first cellular base station; and retain the conditional switching information received from the first cellular base station after the first conditional switching.

[0117] According to some embodiments, the processor is further configured to cause the wireless device to: perform a second conditional handover using the conditional handover information received from the first cellular base station.

[0118] According to some embodiments, the first conditional handover is from a first cell provided by a first cellular base station to a second cell provided by a second cellular base station, wherein the second conditional handover is from the second cell to a third cell provided by a third cellular base station.

[0119] According to some embodiments, the processor is further configured to cause the wireless device to: receive a handover command indicating release of conditional handover information; perform handover according to the handover command; and release the conditional handover information based at least in part on the handover command.

[0120] According to some embodiments, the processor is further configured to cause the wireless device to: receive a handover command that maintains the release of conditional handover information; perform handover in accordance with the handover command; and retain the conditional handover information received from the first cellular base station based at least in part on the handover command.

[0121] According to some embodiments, the processor is further configured to cause the wireless device to: provide capability information to the first cellular base station, wherein the capability information indicates that the wireless device supports conditional switching information for configuring continuous conditional switching.

[0122] According to some embodiments, the capability information also indicates a maximum amount of conditional handover information supported by the wireless device.

[0123] Another set of embodiments may include a wireless device comprising: an antenna; a radio component operably coupled to the antenna; and a processor operably coupled to the radio component; wherein the wireless device is configured to: when the wireless device is connected to a first cell provided by a cellular base station, receive conditional switching information from the cellular base station, wherein the conditional switching information includes information for performing conditional switching from the first cell to at least a second cell and information for performing conditional switching from the second cell to at least a third cell; use the conditional switching information to perform conditional switching from the first cell to the second cell, wherein after the conditional switching from the first cell to the second cell, the wireless device is connected to the second cell; and use the conditional switching information to perform conditional switching from the second cell to the third cell, wherein after the conditional switching from the second cell to the third cell, the wireless device is connected to the third cell.

[0124] According to some embodiments, information for performing conditional switching from a first cell to a second cell includes configuration information for the second cell, wherein after the conditional switching from the first cell to the second cell, the wireless device communicates with the second cell according to the configuration information for the second cell.

[0125] According to some embodiments, information for performing conditional switching from a first cell to a second cell specifies one or more conditions required to perform conditional switching from the first cell to the second cell, wherein the wireless device is further configured to: determine that one or more conditions required to perform conditional switching from the first cell to the second cell are satisfied when connected to the first cell, wherein the conditional switching from the first cell to the second cell is performed at least in part based on determining that one or more conditions required to perform conditional switching from the first cell to the second cell are satisfied when connected to the first cell.

[0126] According to some embodiments, information for performing conditional switching from a second cell to a third cell specifies one or more conditions required to perform conditional switching from the second cell to the third cell, wherein the wireless device is further configured to: determine that one or more conditions required to perform conditional switching from the second cell to the third cell are satisfied when connected to the second cell, wherein the conditional switching from the second cell to the third cell is performed at least in part based on determining that one or more conditions required to perform conditional switching from the second cell to the third cell are satisfied when connected to the second cell.

[0127] According to some embodiments, the wireless device is further configured to: receive conditional handover information from a cellular base station, the conditional handover information including information for performing conditional handover from the first cell to the third cell and information for performing conditional handover from the third cell to the second cell.

[0128] According to some embodiments, the wireless device is further configured to retain the conditional handoff information received from the first cellular base station until an indication to release the conditional handoff information is received.

[0129] Another set of embodiments may include a first cellular base station configured to provide a first cell, comprising: an antenna; a radio component operably coupled to the antenna; and a processor operably coupled to the radio component; wherein the first cellular base station is configured to: provide a conditional handover request to a second cellular base station configured to provide a second cell; receive a response to the conditional handover request from the second cellular base station, wherein the response includes information for performing a conditional handover from the second cell to at least a third cell; and provide conditional handover information to a wireless device, wherein the conditional handover information includes information for performing a conditional handover from the first cell to at least the second cell and information for performing a conditional handover from the second cell to at least the third cell.

[0130] According to some embodiments, the first cellular base station is further configured to: provide a conditional switching request to a third cellular base station, the third cellular base station being configured to provide a third cell; receive a response to the conditional switching request from the third cellular base station, wherein the response includes information conditional switching information for performing conditional switching from the third cell to at least the second cell, wherein the conditional switching information also includes information for performing conditional switching from the first cell to at least the third cell and information for performing conditional switching from the third cell to at least the second cell.

[0131] According to some embodiments, the first cellular base station is further configured to: provide a handover command to the wireless device, wherein the handover command indicates a release of the conditional handover information.

[0132] According to some embodiments, the first cellular base station is further configured to provide a handover command to the wireless device, wherein the handover command maintains release of the conditional handover information.

[0133] According to some embodiments, the first cellular base station is further configured to: receive capability information from the wireless device, wherein the capability information indicates that the wireless device supports conditional switching information for configuring continuous conditional switching, wherein the first cellular base station is configured to provide the conditional switching information to the wireless device based at least in part on the capability information received from the wireless device.

[0134] According to some embodiments, the conditional handover request indicates a set of candidate cells for which conditional handover information is requested, wherein the set of candidate cells for which conditional handover information is requested includes at least the second cell and the third cell.

[0135] According to some embodiments, the response to the conditional handover request from the second cellular base station also includes cell configuration information for the second cell, wherein the information for performing conditional handover from the second cell to at least a third cell specifies one or more conditions required to perform conditional handover from the second cell to the third cell.

[0136] Another exemplary embodiment may include a device comprising: an antenna; a radio component coupled to the antenna; and a processing element operably coupled to the radio component, wherein the device is configured to implement any or all of the foregoing examples.

[0137] Another exemplary embodiment may include a method comprising: performing, by a device, any or all of the foregoing examples.

[0138] Further example embodiments may include a non-transitory computer-accessible storage medium including program instructions that, when executed at a device, cause the device to implement any or all of any of the foregoing examples.

[0139] Another exemplary embodiment may include a computer program comprising instructions for performing any or all of any of the foregoing examples.

[0140] Another exemplary embodiment may include an apparatus including means for performing any or all of the elements of any of the preceding examples.

[0141] Another exemplary set of embodiments may include an apparatus comprising a processing element configured to cause a wireless device to perform any or all elements of any of the foregoing examples.

[0142] It is understood that the use of personally identifiable information should be subject to privacy policies and practices that are generally recognized to meet or exceed industry or government requirements for maintaining user privacy. Specifically, personally identifiable information data should be managed and processed to minimize the risk of unintentional or unauthorized access or use, and the nature of the authorized use should be clearly stated to users.

[0143] Embodiments of the present invention may be implemented in any of a variety of forms. For example, in some embodiments, the present invention may be implemented as a computer-implemented method, a computer-readable storage medium, or a computer system. In other embodiments, one or more custom-designed hardware devices such as ASICs may be used to implement the present invention. In other embodiments, one or more programmable hardware elements such as FPGAs may be used to implement the present invention.

[0144] In some embodiments, a non-transitory computer-readable memory medium (e.g., a non-transitory memory element) may be configured such that it stores program instructions and / or data, wherein if the program instructions are executed by a computer system, the computer system is caused to perform a method, such as any of the method embodiments described herein, or any combination of the method embodiments described herein, or any subset of any method embodiments described herein, or any combination of such subsets.

[0145] In some embodiments, a device (e.g., a UE) may be configured to include a processor (or a group of processors) and a memory medium (or a memory element), wherein the memory medium stores program instructions, wherein the processor is configured to read and execute the program instructions from the memory medium, wherein the program instructions are executable to implement any of the various method implementations described herein (or any combination of the method implementations described herein, or any subset of any method implementations described herein or any combination of such subsets). The device may be implemented in any of various forms.

[0146] Although the above embodiments have been described in considerable detail, numerous variations and modifications will become apparent to those skilled in the art once the above disclosure is fully appreciated. It is intended that the following claims be interpreted to encompass all such variations and modifications.

Claims

1. A device comprising: A processor configured to, when executing instructions stored in the memory, perform operations comprising: providing capability information to the first cellular base station, wherein the capability information indicates that the wireless device supports configuration of continuous conditional handoff; receiving conditional handover information from the first cellular base station, wherein the conditional handover information includes information supporting execution of continuous conditional handover and explicitly indicates that the conditional handover information is maintained after the handover is completed; performing a first conditional handover using the conditional handover information received from the first cellular base station; and The conditional handoff information received from the first cellular base station is retained after the first conditional handoff.

2. The apparatus of claim 1, wherein the operations further comprise: A second conditional handoff is performed using the conditional handoff information received from the first cellular base station.

3. The device according to claim 2, wherein the first conditional handover is from a first cell provided by the first cellular base station to a second cell provided by a second cellular base station, The second conditional switching is from the second cell to a third cell provided by a third cellular base station or to the first cell provided by the first cellular base station.

4. The apparatus of claim 1, wherein the operations further comprise: receiving a handover command instructing to release the conditional handover information; Execute switching according to the switching command; as well as The conditional handover information is released based at least in part on the handover command.

5. The apparatus of claim 1, wherein providing the conditional handover information reduces the likelihood of a handover failure occurring after performing the conditional handover due to a reduction in time on a target cell of the conditional handover.

6. The device according to claim 1, The capability information further indicates a maximum amount of conditional switching information supported by the wireless device.

7. A wireless device comprising: antenna; a radio component operably coupled to the antenna; and a processor operatively coupled to the radio; The wireless device is configured to: providing capability information to a cellular base station, wherein the capability information indicates that the wireless device supports configuration of continuous conditional handover; When the wireless device is connected to a first cell provided by the cellular base station, receiving conditional handover information from the cellular base station, wherein the conditional handover information explicitly indicates that the conditional handover information is maintained after the handover is completed and includes information for performing conditional handover from the first cell to at least a second cell and information for performing conditional handover from the second cell to at least a third cell; performing a conditional handover from the first cell to the second cell using the conditional handover information, wherein the wireless device is connected to the second cell after the conditional handover from the first cell to the second cell; as well as A conditional handover from the second cell to the third cell is performed using the conditional handover information, wherein after the conditional handover from the second cell to the third cell, the wireless device is connected to the third cell.

8. The wireless device according to claim 7, The information for performing conditional handover from the first cell to the second cell includes configuration information for the second cell, and after the conditional handover from the first cell to the second cell, the wireless device communicates with the second cell according to the configuration information for the second cell.

9. The wireless device of claim 7, wherein the information for performing conditional handover from the first cell to the second cell specifies one or more conditions for performing conditional handover from the first cell to the second cell, wherein the wireless device is further configured to: determining that the one or more conditions for performing a conditional handover from the first cell to the second cell while connected to the first cell are satisfied, Wherein conditional handover from the first cell to the second cell is performed based at least in part on determining that the one or more conditions for performing conditional handover from the first cell to the second cell while connected to the first cell are satisfied.

10. The wireless device of claim 7, wherein the information for performing conditional handover from the second cell to the third cell specifies one or more conditions for performing conditional handover from the second cell to the third cell, wherein the wireless device is further configured to: determining that the one or more conditions for performing a conditional handover from the second cell to the third cell while connected to the second cell are satisfied, Wherein the conditional handover from the second cell to the third cell is performed based at least in part on determining that the one or more conditions for performing the conditional handover from the second cell to the third cell while connected to the second cell are satisfied.

11. The wireless device of claim 7, wherein the wireless device is further configured to: Conditional handover information is received from the cellular base station, the conditional handover information including information for performing conditional handover from the first cell to the third cell and information for performing conditional handover from the third cell to the second cell.

12. The wireless device of claim 7, wherein the wireless device is further configured to: The conditional handover information received from the cellular base station is retained until an instruction to release the conditional handover information is received.

13. A first cellular base station, comprising: antenna; a radio operably coupled to the antenna; and a processor operatively coupled to the radio; The first cellular base station is configured as: providing a first cell; providing a conditional handover request to a second cellular base station, the second cellular base station being configured to provide a second cell; receiving a response to the conditional handover request from the second cellular base station, wherein the response includes first information for performing a conditional handover from the second cell to at least a third cell; receiving capability information from a wireless device, wherein the capability information indicates that the wireless device supports configuration of continuous conditional handover; as well as Second conditional handover information is provided to the wireless device via the first cell, wherein the second conditional handover information explicitly indicates that the second conditional handover information is maintained after the handover is completed and includes first partial information for performing conditional handover from the first cell to at least the second cell and second partial information for performing conditional handover from the second cell to at least a third cell.

14. The first cellular base station according to claim 13, wherein the first cellular base station is further configured to: providing a conditional handover request to a third cellular base station, the third cellular base station being configured to provide the third cell; receiving a response to the conditional handover request from the third cellular base station, wherein the response includes third conditional handover information for performing conditional handover from the third cell to at least the second cell, The third conditional handover information further includes third part information for executing conditional handover from the first cell to at least the third cell and fourth part information for executing conditional handover from the third cell to at least the second cell.

15. The first cellular base station according to claim 13, wherein the first cellular base station is further configured to: A handover command is provided to the wireless device, wherein the handover command indicates a release of the second conditional handover information.

16. The first cellular base station according to claim 13, wherein the first cellular base station is further configured to: A handover command is provided to the wireless device, wherein the handover command indicates to maintain the second conditional handover information.

17. The first cellular base station according to claim 13, wherein the first cellular base station is further configured to: The second conditional handover information is provided to the wireless device based at least in part on the capability information received from the wireless device.

18. The first cellular base station according to claim 13, The conditional handover request indicates a group of candidate cells for which the second conditional handover information is requested, wherein the group of candidate cells for which the second conditional handover information is requested includes at least the second cell and the third cell.

19. The first cellular base station according to claim 13, wherein the response to the conditional handover request from the second cellular base station further includes cell configuration information for the second cell, The first information for performing conditional handover from the second cell to at least the third cell specifies one or more conditions for performing conditional handover from the second cell to the third cell.

20. A method for a wireless device, comprising: providing capability information to a first cellular base station, wherein the capability information indicates that the wireless device supports configuration of continuous conditional handoff; receiving conditional handover information from the first cellular base station, wherein the conditional handover information includes information supporting execution of continuous conditional handover and explicitly indicates that the conditional handover information is maintained after the handover is completed; performing a first conditional handover using the conditional handover information received from the first cellular base station; and The conditional handoff information received from the first cellular base station is retained after the first conditional handoff.

21. The method according to claim 20, further comprising: A second conditional handoff is performed using the conditional handoff information received from the first cellular base station.

22. The method according to claim 21, wherein the first conditional handover is from a first cell provided by the first cellular base station to a second cell provided by a second cellular base station, The second conditional switching is from the second cell to a third cell provided by a third cellular base station or to the first cell provided by the first cellular base station.

23. The method of claim 20, further comprising: receiving a handover command instructing to release the conditional handover information; Execute switching according to the switching command; as well as The conditional handover information is released based at least in part on the handover command.

24. The method of claim 20, wherein providing the conditional handover information reduces the likelihood of a handover failure occurring after performing the conditional handover due to a reduction in time on a target cell of the conditional handover.

25. The method according to claim 20, The capability information further indicates a maximum amount of conditional switching information supported by the wireless device.

26. A method for a wireless device, comprising: providing capability information to a cellular base station, wherein the capability information indicates that the wireless device supports configuration of continuous conditional handover; When the wireless device is connected to a first cell provided by the cellular base station, receiving conditional handover information from the cellular base station, wherein the conditional handover information explicitly indicates that the conditional handover information is maintained after the handover is completed and includes information for performing conditional handover from the first cell to at least a second cell and information for performing conditional handover from the second cell to at least a third cell; performing a conditional handover from the first cell to the second cell using the conditional handover information, wherein the wireless device is connected to the second cell after the conditional handover from the first cell to the second cell; as well as A conditional handover from the second cell to the third cell is performed using the conditional handover information, wherein after the conditional handover from the second cell to the third cell, the wireless device is connected to the third cell.

27. The method according to claim 26, The information for performing conditional handover from the first cell to the second cell includes configuration information for the second cell, and after the conditional handover from the first cell to the second cell, the wireless device communicates with the second cell according to the configuration information for the second cell.

28. The method of claim 26, wherein the information for performing conditional handover from the first cell to the second cell specifies one or more conditions for performing conditional handover from the first cell to the second cell, wherein the method further comprises: determining that the one or more conditions for performing a conditional handover from the first cell to the second cell while connected to the first cell are satisfied, Wherein conditional handover from the first cell to the second cell is performed based at least in part on determining that the one or more conditions for performing conditional handover from the first cell to the second cell while connected to the first cell are satisfied.

29. The method of claim 26, wherein the information for performing conditional handover from the second cell to the third cell specifies one or more conditions for performing conditional handover from the second cell to the third cell, wherein the method further comprises: determining that the one or more conditions for performing a conditional handover from the second cell to the third cell while connected to the second cell are satisfied, Wherein the conditional handover from the second cell to the third cell is performed based at least in part on determining that the one or more conditions for performing the conditional handover from the second cell to the third cell while connected to the second cell are satisfied.

30. The method of claim 26, wherein the method further comprises: Conditional handover information is received from the cellular base station, the conditional handover information including information for performing conditional handover from the first cell to the third cell and information for performing conditional handover from the third cell to the second cell.

31. The method of claim 26, wherein the method further comprises: The conditional handover information received from the cellular base station is retained until an instruction to release the conditional handover information is received.

32. A method for a first cellular base station, the method comprising: By the first cellular base station: providing a first cell; providing a conditional handover request to a second cellular base station, the second cellular base station being configured to provide a second cell; receiving a response to the conditional handover request from the second cellular base station, wherein the response includes first information for performing a conditional handover from the second cell to at least a third cell; receiving capability information from a wireless device, wherein the capability information indicates that the wireless device supports configuration of continuous conditional handover; as well as Second conditional handover information is provided to the wireless device via the first cell, wherein the second conditional handover information explicitly indicates that the second conditional handover information is maintained after the handover is completed and includes first partial information for performing conditional handover from the first cell to at least the second cell and second partial information for performing conditional handover from the second cell to at least a third cell.

33. The method of claim 32, further comprising: providing a conditional handover request to a third cellular base station, the third cellular base station being configured to provide the third cell; receiving a response to the conditional handover request from the third cellular base station, wherein the response includes third conditional handover information for performing conditional handover from the third cell to at least the second cell, The third conditional handover information further includes third part information for executing conditional handover from the first cell to at least the third cell and fourth part information for executing conditional handover from the third cell to at least the second cell.

34. The method of claim 32, further comprising: A handover command is provided to the wireless device, wherein the handover command indicates a release of the second conditional handover information.

35. The method of claim 32, further comprising: A handover command is provided to the wireless device, wherein the handover command indicates to maintain the second conditional handover information.

36. The method of claim 32, further comprising: The second conditional handover information is provided to the wireless device based at least in part on the capability information received from the wireless device.

37. The method according to claim 32, The conditional handover request indicates a group of candidate cells for which the second conditional handover information is requested, wherein the group of candidate cells for which the second conditional handover information is requested includes at least the second cell and the third cell.

38. The method according to claim 32, wherein the response to the conditional handover request from the second cellular base station further includes cell configuration information for the second cell, The first information for performing conditional handover from the second cell to at least the third cell specifies one or more conditions for performing conditional handover from the second cell to the third cell.

39. A non-transitory computer-readable storage medium having program instructions stored thereon, the program instructions being executable by a processor to cause a wireless device to implement the operation of any one of the methods of claims 20 to 31.

40. A non-transitory computer-readable storage medium having program instructions stored thereon, the program instructions being executable by a processor to cause a wireless device to implement the operation of any one of the methods of claims 32 to 38.

41. A computer program product comprising instructions which, when executed by a computer, cause the computer to perform the method according to any one of claims 20 to 31.

42. A computer program product comprising instructions which, when executed by a computer, cause the computer to perform the method according to any one of claims 32 to 38.

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