Methods, communication devices and infrastructure equipment

Abstract

A method of operating a communication device is provided. The method comprises receiving, from a source infrastructure equipment to which the communication device is connected, one or more conditional low layer trigger mobility, LTM, handover commands, wherein each conditional LTM handover command comprises an indication of at least one target infrastructure equipment and an indication of one or more conditions under which the communication device is to perform an LTM handover procedure to hand over from the source infrastructure equipment to the target infrastructure equipment. Here, the LTM handover procedure consists of signaling at a physical layer and / or at a medium access control, MAC, layer at each of the source infrastructure equipment, the target infrastructure equipment and the communication device only.

Description

Technical Field

[0001] This disclosure relates to communication apparatus and infrastructure equipment for wireless communication networks, and methods for operating such communication apparatus and infrastructure equipment for more efficient handling of mobility processes in such wireless communication networks.

[0002] This application claims priority under the Paris Convention to European Patent Application No. EP24166067.9, filed on 25 March 2024, the contents of which are incorporated herein by reference. Background Technology

[0003] The “Background Art” description provided herein is intended to provide a general overview of the context of this disclosure. To the extent described in this Background Art section, the work of the currently named inventors, and other aspects of this description that do not constitute prior art at the time of filing, are not expressly or implicitly acknowledged as prior art to this invention.

[0004] Previous-generation mobile telecommunications systems (such as those based on the UMTS and LTE architectures defined by 3GPP) can support a wider range of services than the simple voice and messaging services offered by previous-generation mobile telecommunications systems. For example, with the improved radio interface and enhanced data rates provided by LTE systems, users can enjoy high-speed data applications, such as mobile video streaming and mobile video conferencing, which were previously only available through fixed-line data connections. Therefore, the demand for deploying such networks is very strong, and the coverage area of ​​these networks (i.e., the areas where the network can be accessed) is expected to continue to increase rapidly.

[0005] Current and future wireless communication networks are expected to routinely and efficiently support communication with an increasingly wide range of devices, involving a broader range of data traffic characteristics and types than existing systems are optimized to support. For example, future wireless communication networks are expected to need to efficiently support communication with a variety of devices, including low-complexity devices, machine-type communication (MTC) devices, high-resolution video displays, virtual reality headsets, extended reality (XR), and so on. Some of these different types of devices may be deployed in very large numbers, such as low-complexity devices used to support the “Internet of Things” (IoT), and may typically involve transmitting relatively small amounts of data with relatively high latency tolerance. Other types of devices (such as devices supporting high-definition video streaming) may involve transmitting relatively large amounts of data with relatively low latency tolerance. Other types of devices (such as devices used for autonomous vehicle communication and other critical applications) may be characterized by data that should be transmitted over the network with low latency and high reliability. Individual device types may also involve different traffic characteristics / features depending on the application they are running. For example, when a smartphone is running a video streaming application (high downlink data), efficient support for data exchange with that smartphone may require different considerations compared to when it is running an internet browsing application (sporadic uplink and downlink data) or being used by emergency responders for voice communication in emergency scenarios (where data is subject to strict reliability and latency requirements).

[0006] Given the above, it is anticipated that current wireless communication networks (such as those that can be called 5G or New Radio (NR) systems / New Radio Access Technology (RAT) systems, or indeed future 6G wireless communication, as well as future iterations / versions of existing systems) will need to efficiently support connections to a wide variety of devices, involving different applications and data traffic characteristics and requirements. The need to support these new use cases and scenarios presents new challenges to efficiently handling communications in wireless communication systems. Summary of the Invention

[0007] This disclosure may help resolve or mitigate at least some of the problems discussed above.

[0008] Some embodiments of this technology can provide a method for operating a communication device. The method includes receiving one or more conditional lower-layer triggered mobility LTM handover commands from a source infrastructure device to which the communication device is connected, wherein each conditional LTM handover command includes an indication of at least one target infrastructure device and an indication of one or more conditions, and if these conditions are met, the communication device will perform an LTM handover procedure to switch from the source infrastructure device to the target infrastructure device. Here, the LTM handover procedure only includes physical layer signaling at each of the source infrastructure device, the target infrastructure device, and the communication device, and / or media access control (MAC) layer signaling at each of the source infrastructure device, the target infrastructure device, and the communication device.

[0009] Such implementations of the present technology (in addition to methods of operating communication devices, methods of operating infrastructure equipment, communication devices and infrastructure equipment, circuits for communication devices and infrastructure equipment, wireless communication systems, computer programs and computer-readable storage media) can enable more efficient handling of mobility processes in such wireless communication networks.

[0010] The various aspects and features of this disclosure are defined in the appended claims.

[0011] It should be understood that the foregoing general description and the following detailed description are exemplary and not intended to limit the technology. The described embodiments and their further advantages will be best understood with reference to the following detailed description taken in conjunction with the accompanying drawings. Attached Figure Description

[0012] A more complete understanding of this disclosure and its many accompanying advantages will be readily obtained when the following detailed description is considered in conjunction with the accompanying drawings, in which the same reference numerals denote the same or corresponding parts in various views, and wherein: Figure 1 Some aspects of an LTE-type wireless telecommunications system that can be configured to operate according to certain embodiments of this disclosure are illustrated schematically; Figure 2 Some aspects of an NR-type wireless telecommunications system that can be configured to operate according to certain embodiments of this disclosure are illustrated schematically; Figure 3 This is a schematic block diagram of exemplary infrastructure equipment and communication apparatus that can be configured to operate according to certain embodiments of this disclosure; Figure 4A This is a diagram showing the gNB distributed unit (DU) and gNB control unit (CU) communicating via the F1 interface; Figure 4B They are respectively by Figure 4AThe diagram shows a schematic representation of the protocol stack used for transmitting control plane data, illustrating the operations of gNB DU and gNB CU. Figure 4C They are respectively by Figure 4A The diagram shown illustrates the gNB DU and gNB CU operations as a schematic representation of the protocol stack used to transmit user plane data. Figure 5 This schematically illustrates the division of gNB functionality among CU-CP, CU-UP, and DU according to the current architecture; Figure 6 It is an exemplary schematic block diagram of the source infrastructure equipment that controls the switching of communication devices to target infrastructure equipment; Figure 7 This schematically illustrates the traditional conditional switching process; Figure 8 This shows the range of Layer 1 / Layer 2 triggered mobility (LTM) in the current 3GPP specification; Figure 9 This is copied from [6] and an exemplary message sequence of LTM according to the current 3GPP specification is shown; Figure 10 A partial schematic and partial message flow diagram representation of a wireless communication system according to an embodiment of the present technology is shown, the system including communication devices and infrastructure equipment; Figure 11 A first message flow diagram is shown illustrating how an LTM cell handover command with execution conditions is signaled according to an embodiment of the present technology; Figure 12 A second message flow diagram illustrating how resources of a target cell included in an LTM cell handover command are allocated, released, or activated according to an embodiment of the present technology is shown; and Figure 13 A third message flow diagram is shown illustrating how a user equipment (UE) synchronizes with a gNB in ​​the uplink and downlink before transmitting an LTM cell handover command according to an embodiment of the present technology. Detailed Implementation

[0013] 4G (Long Term Evolution) Advanced Radio Access Technology

[0014] Figure 1 A schematic diagram is provided illustrating some basic functions of a mobile telecommunications network / system 6 that typically operates according to LTE principles, but the system may also support other radio access technologies and may be adapted to implement the embodiments of this disclosure described herein. Figure 1Certain aspects of the various components and their corresponding operating modes are well known and defined in relevant standards managed by the 3GPP (RTM) organization, and have also been described in many relevant books (e.g., Holma H and Toskala A [1]). It should be understood that operational aspects of the telecommunications network discussed herein that are not specifically described (e.g., aspects relating to specific communication protocols and physical channels used for communication between different components) can be implemented according to any known technology, such as according to relevant standards and known proposed modifications and additions to relevant standards.

[0015] Network 6 includes multiple base stations 1 connected to core network 2, which may be, for example, an evolved packet core (EPC). Each base station provides coverage area 3 (i.e., a cell), within which data can be transmitted to and from communication device 4. Although Figure 1 Each base station 1 is shown as a single entity, but those skilled in the art will understand that some functions of a base station can be performed by distributed, interconnected components (e.g., antennas, remote radio heads, amplifiers, etc.). Overall, one or more base stations can form a radio access network.

[0016] Data is transmitted from base station 1 to communication device 4 within its corresponding coverage area 3 via radio downlink (DL). Data is transmitted from communication device 4 to base station 1 via radio uplink (UL). Core network 2 routes data to and from communication device 4 via the corresponding base station 1 and provides functions such as authentication, mobility management, and billing. Terminal devices may also be referred to as mobile stations, user equipment (UE), user terminals, mobile radios, communication devices, etc. Services provided by core network 2 may include connections to the Internet or external telephone services. Core network 2 can also track the location of communication device 4 so that it can effectively contact (i.e., page) communication device 4 to transmit downlink data to communication device 4.

[0017] Base stations, as examples of network infrastructure equipment, may also be referred to as transceiver stations, Node Bs, e-Node Bs, eNBs, g-Node Bs, gNBs, etc. In this regard, different terms are generally associated with elements that provide substantially equivalent functionality in different generations of wireless telecommunication systems. However, certain embodiments of this disclosure can be implemented equivalently in different generations of wireless telecommunication systems, and for simplicity, certain terms may be used regardless of the underlying network architecture. That is, the use of specific terms for certain exemplary embodiments is not intended to indicate that these embodiments are limited to the specific generation of networks most relevant to the specific terms.

[0018] New radio access technology (5G)

[0019] Figure 2An exemplary configuration of a wireless communication network using some terminology proposed for and used in NR and 5G is shown. Figure 2 In this configuration, multiple Transmit and Receive Points (TRPs) 10 are connected to Distributed Control Units (DUs) 41, 42 via a connection interface represented as line 16. Each TRP 10 is arranged to transmit and receive signals via a wireless access interface within the available radio frequency bandwidth of the wireless communication network. Thus, within the range of radio communication performed via the wireless access interface, each TRP 10 forms a cell (represented by circle 12) of the wireless communication network. Therefore, wireless communication devices 14 within the radio communication range provided by cell 12 can transmit signals to and receive signals from TRPs 10 via the wireless access interface. Each Distributed Unit 41, 42 is connected to a Central Unit (CU) 40 (which may be referred to as a control node) via interface 46. The Central Unit 40 is then connected to a core network 20 (e.g., referred to as 5GC), which may contain all other functions required to transmit data to and from wireless communication devices, and may be connected to other networks 30.

[0020] Figure 2 The components of the wireless access network shown in the figure can be similar to those in the reference. Figure 1 The example describes the operation of the corresponding components in an LTE network. It should be understood that... Figure 2 The undescribed operational aspects of the telecommunications network represented herein, as well as other networks discussed in accordance with embodiments of this disclosure (e.g., aspects relating to specific communication protocols and physical channels for communication between different elements), can be implemented according to any known technology, such as methods currently used to implement such operational aspects of wireless telecommunications systems (e.g., according to relevant standards).

[0021] Figure 2 The TRP 10 may, in some cases, have functions corresponding to a base station or eNodeB in an LTE network. Similarly, the communication device 14 may have functions corresponding to a UE device 4 known for operation in an LTE network. Therefore, it is understood that the operational aspects of the new RAT network (e.g., in terms of specific communication protocols and physical channels used for communication between different components) may differ from known operational aspects from LTE or other known mobile telecommunications standards. However, it is also understood that each core network component, base station, and communication device of the new RAT network will be functionally similar to the core network components, base station, and communication device of an LTE wireless communication network, respectively.

[0022] In terms of a wide range of advanced features, connectivity Figure 2 The core network 20 of the new RAT telecommunications system shown can be broadly regarded as being related to... Figure 1Corresponding to the core network 2 shown, and the corresponding central unit 40 and its associated distributed unit / TRP 10 can be broadly regarded as providing the same... Figure 1 The function corresponding to base station 1. The term "network infrastructure equipment / access node" can be used to cover these elements as well as more conventional base station type elements of wireless telecommunications systems. Depending on the application at hand, the responsibility for scheduling transmissions on the radio interface between the corresponding distributed unit and the communication device may lie with the control node / central unit and / or distributed unit / TRP. Communication device 14 represents the function of... Figure 2 Within the coverage area of ​​the first communication cell 12. Therefore, the communication device 14 can exchange signaling with the first central unit 40 in the first communication cell 12 through one of the distributed units / TRP 10 associated with the first communication cell 12.

[0023] It can be understood further. Figure 2 This is merely one example of an architecture proposed for a new RAT-based telecommunications system that can employ the methods described in this document, and the functionality disclosed herein can also be applied to aspects of wireless telecommunications systems with different architectures.

[0024] Therefore, certain embodiments of this disclosure discussed herein can be implemented according to various different architectures (such as...) Figure 1 and Figure 2 The example architecture shown is implemented in a wireless telecommunications system / network. Therefore, it can be understood that a particular wireless telecommunications architecture in any given implementation is not primarily relevant to the principles described herein. In this regard, certain embodiments of this disclosure can be described in the general context of communication between network infrastructure devices / access nodes and communication devices, wherein the specific nature of the network infrastructure devices / access nodes and communication devices will depend on the network infrastructure implemented at hand. For example, in some scenarios, the network infrastructure devices / access nodes may include base stations, such as… Figure 1 The adapter shown is an LTE-type base station 1 that provides functionality according to the principles described herein, while in other examples, network infrastructure equipment may include... Figure 2 The type of adapter shown is provided to control unit / control node 40 and / or TRP 10 to provide functionality according to the principles described herein.

[0025] Figure 3 Provided Figure 2 A more detailed illustration of some components of the network is shown. Figure 3 In, such as Figure 2The TRP 10 shown, in simplified representation, includes a wireless transmitter 30, a wireless receiver 32, and a controller or control processor 34, operable to control the transmitter 30 and the wireless receiver 32 to transmit and receive radio signals to one or more UEs 14 within the cell 12 formed by the TRP 10. Figure 3 As shown, example UE 14 is shown as including a corresponding transmitter 49, receiver 48 and controller 44, controller 44 being configured to control transmitter 49 and receiver 48 to transmit signals representing uplink data to transmit signals representing uplink data to a wireless communication network via a radio access interface formed by TRP 10, and to receive downlink data as signals transmitted by transmitter 30 and received by receiver 48 in accordance with normal operation.

[0026] Transmitters 30, 49 and receivers 32, 48 (and other transmitters, receivers, and transceivers described in conjunction with examples and embodiments of this disclosure) may include radio frequency filters and amplifiers, as well as signal processing components and means, for transmitting and receiving radio signals, for example, according to the 5G / NR standard. Controllers 34, 44 (and other controllers described in conjunction with examples and embodiments of this disclosure) may be, for example, microprocessors, CPUs, or dedicated chipsets, configured to execute instructions stored on a computer-readable medium, such as non-volatile memory. The processing steps described herein may be executed, for example, by a microprocessor in conjunction with random access memory according to instructions stored on a computer-readable medium. The transmitters, receivers, and controllers in... Figure 3 The components are shown schematically as discrete elements for ease of representation. However, it will be understood that the functionality of these components can be provided in various different ways, such as using one or more appropriately programmed programmable computers, or one or more appropriately configured application-specific integrated circuits / circuits / chips / chipsets. As will be understood, infrastructure equipment / TRP / base stations and UE / communication devices will generally include various other components associated with their operational functions.

[0027] like Figure 3 As shown, TRP 10 also includes a network interface 50 connected to DU 42 via physical interface 16. Therefore, network interface 50 provides a communication link for data and signaling traffic from TRP 10 to core network 20 via DU 42 and CU 40.

[0028] The interface 46 between DU 42 and CU 40 is referred to as the F1 interface, which can be a physical or logical interface. The F1 interface 46 between CU and DU can operate according to 3GPP technical specifications [2] and [3] and can be formed by fiber optic or other wired or wireless high-bandwidth connections. In one example, the connection 16 from TRP 10 to DU 42 is implemented via fiber optic. The connection between TRP 10 and core network 20 can be collectively referred to as the backhaul, which includes the interface 16 from network interface 50 of TRP 10 to DU 42 and the F1 interface 46 from DU 42 to CU 40.

[0029] As those familiar with 5G architecture will understand, CU 40 can be a logical node carrying the Radio Resource Control (RRC) protocol, Serving Data Adaptation Protocol (SDAP), and Packet Data Convergence Protocol (PDCP) of a gNB. Alternatively, CU 40 can be a logical node carrying the RRC and PDCP protocols of an en-gNB (i.e., a gNB capable of connecting to both an EPC and an eNB and which can be understood as, for example, a secondary node (SgNB) used in a dual-connectivity scenario). CU 40 partially controls the operation of one or more DU 40s and terminates the F1 interface 46 for the DU it controls. DU 42 can be a logical node carrying the Radio Link Control (RLC), Media Access Control (MAC), and Physical (PHY) layers of a gNB or en-gNB. The operation of DU 42 is partially controlled by CU 40, and DU 42 terminates the F1 interface 46 for that CU 40.

[0030] Although Figure 2 or Figure 3 Not shown, but those skilled in the art familiar with 5G architecture will recognize that CU 40 can be further divided into CU-CP, which performs the control plane functions of CU 40, and CU-UP, which performs the user plane functions of CU 40 (see, for example, [4]). More specifically, CU-CP may be a logical node of the control plane portion of the RRC and PDCP protocols of CU 40 carrying a gNB or en-gNB. CU-CP terminates its connection to the E1 interface of CU-UP and the F1-C interface of DU 42. As will be understood, the F1-C interface carries the control plane signaling of the F1 interface 46. CU-UP may be a logical node of the user plane portion of the PDCP protocol of CU 40 carrying an en-gNB. Alternatively, CU-UP may be a logical node of the user plane portion of the PDCP protocol and the SDAP protocol of CU 40 carrying a gNB. CU-UP terminates its connection to the E1 interface of CU-CP and the F1-U interface of DU 42. As will be understood, the F1-U interface carries the user plane signaling of the F1 interface 46.

[0031] To understand the exemplary implementation, reference will be made to... Figure 4A , Figure 4B and Figure 4C Explanation used to form Figure 2 and Figure 3 The diagram shows the protocol stack for a standard F1 interface. Regarding the protocol stack, Figure 4A , Figure 4B and Figure 4C Provided by Figure 2 and Figure 3 The illustration shows the processing performed by the components that form a packet data communication path 46 between gNB-DU 42 and gNB-CU 40 via the F1 interface 46. Control plane communication and user plane data are considered separately, although in practice they form the same interface and are processed and transmitted by the same hardware device.

[0032] like Figure 4A As shown, communication is established between gNB DU 42 and gNB CU 40 for the F1 interface 46. However, the control plane protocol stack used to form this interface is shown below. Figure 4B The user plane protocol stack used to transmit user data between gNB-CU 40 and gNB-DU 42 is shown in the figure. Figure 4C In the middle. For example Figure 4B As shown, at the radio network layer, the control plane is formed by the F1 Application Protocol (F1 AP) 301a in gNB-CU 40 and the F1 AP 301b in gNB DU 42. As those skilled in the art familiar with 5G architecture will understand, communication between gNB-CU and gNB DU is conducted via the IPv6 or IPv4 Internet Protocol as specified in [5]. This is in Figure 4B The IP layers 302a in gNB-CU 40 and 302b in gNB-DU 42 are shown in the diagram, forming the IP communication interface 302c. The Flow Control Transport Protocol (SCTP) layers 304a, 304b, and 304c of the protocol stack control end-to-end communication via the IP layer 302, including flow control and quality of service. IP data is transmitted between gNB DU and gNB CU via logical data link layers 306a, 306b, and 306c and physical layers 308a, 308b, and 308c.

[0033] In the user plane, the radio network layer is formed by RLC layers 320a and 320b to create an F1 interface for transmitting user plane data 46. The protocol stack in the transport layer includes the General Packet Radio Service (GPRS) Tunneling Protocol (GTP-U) 322a, 322b, and 322c for user plane data. This protocol controls communication of user plane data for roaming and home users via UDP layers 324a, 324b, and 324c, which in turn controls user plane data communication via IP layers 326a, 326b, and 326c. Similar to the control plane, IP data is transmitted between the gNB DU and gNBCU via logical data link layers 328a, 328b, and 328c and physical layers 330a, 330b, and 330c.

[0034] CU-DU partitioning function

[0035] As described above, CU 40 and DU 42 are configured to perform gNB functions. The allocation or division of gNB functions between CU 40 and DU 42 is discussed in [6]. Such gNB functions include: • Functions for radio resource management: radio bearer control, radio admission control, connection mobility control, and dynamic allocation (scheduling) of resources to the UE in both uplink and downlink. • IP and Ethernet header compression, data encryption, and integrity protection; • When a route to the AMF cannot be determined based on the information provided by the UE, the Access and Mobility Management Function (AMF) is selected during UE attachment. • Routing user plane data to user plane functions (UPF); • Route control plane information to AMF; • Connection establishment and release; • Scheduling and transmission of paging messages; • Scheduling and transmission of system broadcast information (originating from AMF or OAM); • Configuration for measurement and measurement reporting for mobility and scheduling; • Transport layer packet marking in the uplink; • Session management; • Supports network slicing; • QoS flow management and mapping to data radio bearers; • Supports UEs in the RRC_INACTIVE state; • NAS message distribution functionality; • Shared radio access network; • Dual connection; • Tight interconnection between NR and E-UTRA; and • Maintain user plane cellular Internet of Things (CIoT) 5GS optimized security and radio configuration as defined in [7] (ng-eNB only).

[0036] Except for the last function, all the functions listed above can be performed by both gNB and ng-eNB, except for the last function related to security and radio configuration maintenance, which is performed only by ng-eNB. As those skilled in the art will understand, ng-eNB is an eNB that connects a 5G UE to a 5G core network using a 4G LTE air interface. In addition, low-complexity (BL) UEs with reduced bandwidth or UEs in enhanced coverage are supported only by ng-eNB (see, for example, [8]). Furthermore, NB-IoT UEs are supported only by ng-eNB (see, for example, [8]).

[0037] As will be understood, 5G networks are currently deployed in millimeter-wave bands. However, the need for higher-frequency wireless communication in 5G networks is increasing due to the higher communication bandwidth achievable at higher frequencies. Using higher frequencies in wireless communication leads to increased path loss, resulting in smaller cell sizes compared to using lower frequencies. Therefore, denser network deployment may be required to achieve adequate coverage.

[0038] The dense deployment of networks presents several technical challenges to the current 5G architecture, such as reference... Figure 2 and Figure 3 As explained above, DU 42 and CU 40 can be connected via a wired connection 46 (such as fiber optic). Therefore, dense network deployment can increase the number of wired connections required, which is not always feasible. Furthermore, due to the current topology, using a wired connection 46 between CU 40 and DU may result in increased latency. For example, as... Figure 2 The lieutenant general understands that the two DUs 41 and 42 are connected to CU 40 in a “tree topology” via wired connection 46. Therefore, if any direct signaling is required between the two cells 12 (e.g., one cell is provided by DU 41 and the other by DU 42), such signaling must be propagated via CU 40. This can lead to congestion and increased latency, especially when a large number of cells are deployed in close proximity, such as in dense deployment scenarios.

[0039] In addition, the following will refer to Figure 5 As explained in more detail, higher cell density presents technical challenges in providing cell mobility and interference management. Figure 5 This illustrates the functional division of gNBs among CU-CP 40a, CU-UP 40b, and DU 42 based on the current 5G architecture. CU-CP 40a and CU-UP 40b are responsible for implementing the functions described in the reference above. Figure 2 , Figure 3 And the logical nodes of the CU 40 as described in Figure 4. For example... Figure 5 As shown, CU-CP 40a is configured to perform Radio Resource Management (RRM) function 402, Radio Resource Control (RRC) function 403, Packet Data Convergence Protocol Control Plane (PDCP-CP) function 404, Security function 406, Non-Access Stratum (NAS) function 408, User Equipment (UE) Context function 410, and Quality of Service (QoS) function 412. CU-UP 40b is configured to perform Packet Data Convergence Protocol User Plane (PDCP-UP) function 414. DU 42 is configured to perform RLC function 416, MAC function 418, and PHY function 420. It will be understood that the scheduler in DU 42 can be implemented based on the guidelines mentioned in Section 10 of [6].

[0040] Traditional switching (HO)

[0041] Figure 6 A detailed diagram of the switchable wireless communication networks is shown. From Figure 6 It can be understood that communication device 502 switches from the source cell provided by source infrastructure equipment 504 to the target cell provided by target infrastructure equipment 506. For clarity, Figure 6 The source cell and target cell are not shown, but it can be understood that the source cell and target cell can roughly correspond to the combination of the above. Figure 1 and Figure 2 The discussed cells 3 and 12. Source infrastructure equipment 504 and target infrastructure equipment 506 form part of the radio access network to the core network 508. It will be understood that communication device 502 is, for example,... Figure 1 MT4 or Figure 2 and Figure 3 Example of a communication device for UE 14.

[0042] Prior to the handover, communication device 502 transmits signals on the uplink UL and receives signals from source infrastructure device 504 on the downlink DL. Both source infrastructure device 504 and target infrastructure device 506 can be considered as a combination of gNB 101 or control node 221 and TRP 211. Prior to the handover, communication device 502 is shown transmitting uplink data to source infrastructure device 504 via the uplink resource UL of the radio access interface, as generally indicated by dashed arrow 574b. Communication device 502 can similarly be configured to receive downlink data transmitted by source infrastructure device 504 via the downlink resource DL, as indicated by dashed arrow 588b. After the handover, communication device 502 is shown transmitting uplink data to target infrastructure device 506 via the uplink resource UL of the radio access interface, as generally indicated by solid arrow 588a. Communication device 502 can be similarly configured to receive downlink data sent by target infrastructure device 506 via downlink resource DL, as shown by solid arrow 574a from target infrastructure device 506 to communication device 502.

[0043] exist Figure 6 In this configuration, both source infrastructure device 504 and target infrastructure device 506 are connected to the core network 508 via interfaces 578 and 579, which are also connected to controllers 504c and 506c of their respective infrastructure devices. Each of the source infrastructure device 504 and target infrastructure device 506 includes receivers 504b and 506b connected to antennas 504d and 506d, and transmitters 504a and 506a connected to antennas 504d and 506d, respectively. Correspondingly, communication device 502 includes a controller 502c connected to receiver 502b, which receives signals from antenna 502d, and communication device 502 also includes a transmitter 502a connected to antenna 502d.

[0044] Controllers 504c and 506c are configured to control source infrastructure device 504 and target infrastructure device 506, respectively, and may include processor circuitry, which may further include various sub-units / sub-circuits for providing the functions described further below. These sub-units may be implemented as discrete hardware components or as appropriately configured processor circuitry. Therefore, controllers 504c and 506c may include circuitry appropriately configured / programmed to provide the desired functions using conventional programming / configuration techniques for devices in wireless telecommunications systems. Transmitters 504a and 506a and receivers 504b and 506b may include signal processing and RF filters, amplifiers, and circuitry arranged according to conventional methods. For ease of illustration, transmitters 504a and 506a, receivers 504b and 506b, and controllers 504c and 506c are... Figure 6 The components are schematically shown as discrete elements. However, it will be understood that the functionality of these components can be provided in a variety of different ways, such as using one or more appropriately programmed programmable computers, or one or more appropriately configured application-specific integrated circuits / circuit systems / chips / chipsets. It will also be understood that the infrastructure device 504 will generally include a variety of other components associated with its operational functions.

[0045] Accordingly, the controller 502c of the communication device 502 is configured to control the transmitter 502a and the receiver 502b, and may include processor circuitry, which may further include various sub-units / sub-circuits for providing the functions described further below. These sub-units may be implemented as discrete hardware elements or as appropriately configured functions of the processor circuitry. Therefore, the controller 502c may include circuitry appropriately configured / programmed to provide the desired functions using conventional programming / configuration techniques for devices in wireless telecommunications systems. Similarly, the transmitter 502a and receiver 502b may include signal processing and RF filters, amplifiers, and circuitry arranged according to conventional methods. For ease of illustration, the transmitter 502a, receiver 502b, and controller 502c are shown in... Figure 6 The components are schematically shown as discrete elements. However, it will be understood that the functionality of these components can be provided in various different ways, such as using one or more appropriately programmed programmable computers, or one or more appropriately configured application-specific integrated circuits / circuit systems / chips / chipsets. It will also be understood that the communication device 502 will generally include various other components associated with its operational functions, such as power supplies, user interfaces, etc., but for simplicity, these components are not shown in the diagram. Figure 6 As shown in the image.

[0046] Controllers 504c and 502c can be configured to execute instructions stored on a computer-readable medium (such as non-volatile memory). The processing steps described herein can be executed, for example, by a microprocessor in conjunction with random access memory, operating according to the instructions stored on the computer-readable medium.

[0047] Traditional Conditional Switching (CHO)

[0048] NR focuses on enhancing mobility, particularly improving mobility robustness for new services requiring low latency and high reliability, such as URLLC. Situations may arise where the cell currently serving the UE may no longer be suitable, or the radio link between the UE and the source gNB providing coverage in the cell may deteriorate. In such cases, it is generally expected that the UE will switch to a cell served by the target gNB. One configuration method for switching the UE from the source gNB to the target gNB is called "conditional handover."

[0049] Figure 7 An example of conditional switching (CHO) is shown. Figure 7 It is copied from [6], and its contents are incorporated into this paper in their entirety by reference. Figure 7 This schematically illustrates communication between communication device 502, source infrastructure device 504, target infrastructure device 506, other potential target infrastructure devices 511, access and mobility management function (AMF) 512, and user plane function (UPF) 514 in a wireless communication network. Figure 7 In this context, source infrastructure device 504, target infrastructure device 506, and other potential target infrastructure devices 511 are described as "gNB," but it will be understood that other infrastructure devices of the wireless communication network (such as eNB) may be used. AMF 512 and UPF 514 are functions within the core network of the wireless communication network (such as core network 508).

[0050] like Figure 7As shown, prior to handover, communication device 502 transmits user plane data to AMF 512 and UPF 514 via source infrastructure device 504. In step 0, AMF 512 provides mobility control information to source infrastructure device 504. In step 1, communication device 502 reports measurements to source infrastructure device 504. Such measurements may include measurements performed by communication device 502, such as reference signal received power (RSRP), reference signal received quality (RSRQ), and / or signal-to-interference ratio (SINR) of reference signals from source infrastructure device 504, target infrastructure device 506, and / or other potential target infrastructure devices 511. In step 2, source infrastructure device 504 determines the configuration of communication device 502 for conditional handover. In step 3, source infrastructure device 504 sends handover requests to target infrastructure device 506 and other potential target infrastructure devices 511. In response, in step 4, target infrastructure device 506 and other potential target infrastructure devices 511 perform admission control. Then, in step 5, the target infrastructure device 506 and other potential target infrastructure devices 511 send a handover request confirmation to the source infrastructure device 504.

[0051] In response to receiving a handover request confirmation, source infrastructure device 504 sends a conditional handover configuration message to communication device 502 in step 6. The conditional handover configuration message may be a Radio Resource Control (RRC) configuration message. The conditional handover configuration message includes one or more conditions for triggering a handover by communication device 502 from a source cell provided by source infrastructure device 504. For example, one or more conditions in the conditional handover configuration message may include one or more conditions to be met to trigger a handover to a target cell provided by target infrastructure device 506, and one or more other conditions to be met to trigger a handover to another target cell provided by another potential target infrastructure device 511. The conditions included in the conditional handover configuration message are described in more detail below. After receiving the conditional handover configuration message, communication device 502 sends an RRC reconfiguration complete message to source infrastructure device 504. After receiving the conditional handover configuration message, communication device 502 may continuously or periodically evaluate the conditions included in the handover configuration message for triggering the handover to determine whether the conditions for triggering the handover have been met.

[0052] When communication device 502 determines that the conditions for triggering handover have been met, communication device 502 initiates handover. For example, communication device 502 disconnects from the source cell provided by source infrastructure equipment 504 and attaches to the target cell provided by target infrastructure equipment 506. Figure 7In the example shown, communication device 502 determines that the conditions for triggering a handover to target infrastructure device 506 have been met. While communication device 502 evaluates the conditions, source infrastructure device 604 sends an early state transition to other potential target infrastructure devices in step 7a, and subsequent user data from UPF 514 is routed to other potential target infrastructure devices 511 via source infrastructure device 504. In step 8, target infrastructure device 506 determines that the handover of communication device 502 from the source cell provided by source infrastructure device 504 to the target cell provided by target infrastructure device 506 has been successful.

[0053] In response, target infrastructure device 506 sends a handover success message to source infrastructure device 504 in step 8a. In step 8b, source infrastructure device 504 sends an SN state transition message to target infrastructure device 506. Subsequent user data from UPF 514 to the source infrastructure device is routed to target infrastructure device 506. In step 8c, handover cancellation messages are sent from source infrastructure device 504 to the target infrastructure device and other potential target infrastructure devices 511.

[0054] As mentioned above Figure 7 As described in step 6, the source infrastructure device 504 may send a conditional handover configuration message to the communication device 502, which includes one or more conditions for triggering the handover.

[0055] An example of a condition that triggers a handover of communication device 502 is “Event A3” based on Layer 3 (L3) measurement. The condition defined by Event A3 is met if the signal quality of the cell provided by a neighboring infrastructure device (e.g., target infrastructure device 506 or other potential target infrastructure device 511) is higher than the signal quality of the cell provided by the source infrastructure device 504 by a predefined offset. Another example of a condition that triggers a handover of communication device 502 is Event A4 based on L3 measurement. The condition defined by Event A4 is met if the signal quality of the cell provided by the neighboring infrastructure device is greater than an absolute threshold. Another example of a condition that triggers a handover of communication device 502 is Event A5 based on L3 measurement. The condition defined by Event A5 is met if the signal quality of the cell provided by the source infrastructure device 504 is less than an absolute threshold, and the signal quality of the cell provided by the neighboring infrastructure device is greater than an absolute threshold.

[0056] The “signal quality” mentioned in the definitions of events A3, A4, and A5 above can be measured by communication device 502 using one or more signal quality parameters such as RSRP, RSRQ, and SINR. For example, if the measured RSRP of the cell provided by the neighboring infrastructure equipment becomes higher than the measured RSRP of the cell provided by the source infrastructure equipment 504 by a predefined offset, then communication device 502 can determine that the condition outlined in event A3 may have been met. In another example, if the measured RSRP and RSRQ of the cell provided by the neighboring infrastructure equipment become higher than the measured RSRP and RSRQ of the cell provided by the source infrastructure equipment 504 by predefined offsets, then communication device 502 can determine that the condition outlined in event A3 has been met. In version 16 of the 3GPP standard, only one reference signal type and at most two signal quality parameters are supported for measurement when determining whether events A3, A4, and / or A5 are met.

[0057] Therefore, each of events A3, A4, and A5 represents a triggering condition for switching communication device 502 from source infrastructure device 504. To trigger a switch, it may be sufficient to satisfy only one condition included in the conditional switch configuration message, or triggering a switch may require satisfying more than one or all of the conditions in the conditional switch configuration message. In one example, only event A3 is included as a condition, and a switch is triggered if event A3 is satisfied. In another example, both events A3 and A4 are included as conditions, and a switch is triggered if either event A3 or A4 is satisfied. In yet another example, both events A3 and A4 are included as conditions, and a switch is triggered if both events A3 or A4 are satisfied.

[0058] Layer 1 / Layer 2 Triggered Mobility (LTM)

[0059] Version 18 of the 3GPP standard specifies L1 / 2 triggered mobility (LTM) within a CU (including within and between DUs). LTM can also alternatively refer to "Lower-layer Triggered Mobility." The operation of LTM itself will be described in more detail in the following paragraphs, but in short, as those skilled in the art will readily understand, LTM refers to UE mobility entirely controlled by Layer 1 (i.e., the physical layer) and Layer 2 (i.e., the data link layer, or more specifically, the MAC layer) of the 5G protocol stack. Both intra-DU and inter-DU LTM (both within the CU) can be referenced... Figure 8 To understand. For example... Figure 8As can be seen in the example, two DUs 82 and 83 are connected to a single CU 81. Each DU 82 and 83 supports two cells, with DU 82 supporting cells 84 and 85, and DU 83 supporting cells 86 and 87. In CU-internal LTM, the UE is handed over between the source cell and the target cell, both of which are controlled by the same CU (via the same or separate DUs), such as for Figure 8 CU 81. For LTM within a DU, Layer 1 and Layer 2 can trigger and control handover for UEs between cells 84 and 85 (controlled by the same DU 82) or between cells 86 and 87 (controlled by the same DU 83). For LTM within a DU, Layer 1 and Layer 2 can trigger and control handover for UEs between one of cells 84 and 85 (controlled by DU 82) and one of cells 86 and 87 (controlled by DU 83) – for example, LTM within a DU might involve a UE handover from cell 87 to cell 84. As of the priority date of this disclosure, LTM within a CU is not specified in the 3GPP standard, but is expected to be specified in version 19 of the 3GPP standard.

[0060] A message sequence proposed for LTM, such as Figure 9 As shown, Figure 9 Copy from [6], in which it is used as Figure 9 Section 2.3.5.2-1 is included. Detailed procedures for LTM are as follows... Figure 9 As shown in [6], the following paragraphs describe... Figure 9 The description is based on that description in [6] and is included in this paper for the purpose of helping to better understand LTM.

[0061] In step 1, UE 91 (in RRC_connection mode) sends a measurement report message to gNB 92 based on L3 measurements. gNB 92 decides to use LTM and initiates candidate cell preparation. In step 2, gNB 92 sends an RRC reconfiguration message to UE 91, which includes the LTM candidate cell configuration of one or more candidate cells. In step 3, UE 91 stores the LTM candidate cell configuration and sends an RRC reconfiguration complete message to gNB 92. In step 4a, UE 91 may perform DL synchronization with the candidate cell before receiving a cell handover command, and in step 4b, UE 91 may perform early timing advance (TA) acquisition with the candidate cell before receiving a cell handover command. This is accomplished via contention-free random access (CFRA) triggered by a physical downlink control channel (PDCCH) command from the source cell, after which UE 91 sends a preamble to the candidate cell. Information identifying the allocated CFRA resources can be indicated in the PDCCH command to achieve shared preamble resources among multiple UE 91s. To minimize data interruption in the source cell due to CFRA directed towards the candidate cell, UE 91 receives a Random Access Response (RAR) from the source cell instead of the candidate cell, or does not receive a RAR at all. Whether a RAR is required is configured by the network and is specific to each candidate cell. If a RAR is not required, the TA value of the candidate cell is indicated in the cell handover command.

[0062] In step 5, UE 91 performs L1 measurements on the configured candidate cells and sends a low-layer measurement report to gNB 92. Then, in step 6, gNB 92 decides to perform a cell handover to the target cell and sends a MAC control element (CE) that triggers the cell handover, including the candidate configuration index of the target cell. UE 91 switches to the configuration of the target cell. In step 7, if the cell handover requires the execution of such a random access procedure, UE 91 performs a random access procedure toward the target cell. Finally, in step 8, UE 91 completes the LTM cell handover procedure by sending an RRC reconfiguration complete message to the target cell. For LTM based on random access (RACH), UE 91 considers the LTM execution procedure to be successfully completed when the random access procedure itself is successfully completed. For LTM without RACH, UE 91 considers the LTM execution procedure to be successfully completed when UE 91 determines that the network has successfully received its first UL data. UE 91 can perform the following multiple times based on the configuration provided in step 2: Figure 9 Steps 4 through 8 are shown for subsequent LTM cell handover.

[0063] In [9], it is noted that some mobility enhancements for LTM should be specified, and several objectives are described. These objectives are copied from [9] below.

[0064] Support for CU inner layer 2 mobility (LTM) [RAN2, RAN3] is specified: Prioritize the scenario where the CU acts as the MN when no DC is configured. As a secondary priority, it supports the case where NR-DC is configured, CU acts as SN, and MCG remains unchanged; As a secondary priority, it supports the scenario where NR-DC and CU are configured as MN and SCG remains unchanged or is released. Note: The case where LTM is configured in both MCG and SCG is excluded; The specification includes support for subsequent LTM mobility procedures designed to avoid RRC; LTM configuration between cell handovers according to version 18; Coordination with SA3 is required for secure key processing; Note: The LTM procedure within the CU in version 18 is considered the baseline for adding in-CU support; measurement-related enhancements for supporting LTM: [RAN2, RAN1]: Measurement-related enhancements are applicable to both inter-CU MCG / SCG LTM and intra-CU MCG / SCG LTM; Specify the necessary components [RAN2, RAN1] required to support event-triggered L1 measurement reporting; RAN1 and RAN2 are progressing independently on their respective MIMO and mobility-enhanced WI event-triggered measurement objectives. Progress is reviewed at RAN#105 to see if any objectives need to be modified to avoid / control any overlap in the work; The specification supports CSI-RS measurements for the LTM process and enables CSI-RS-based beam management on candidate cells and / or other necessary physical layer operations prior to LTM [RAN1]; Support for conditional LTM is specified [RAN2, RAN3, RAN1]; Specify the conditions for triggering LTM in UE evaluation; Designed to support conditional LTMs that include subsequent LTMs; Prioritize LTM between CUs; A checkpoint will be established at RAN#105 to review the target. The RAN WG team may not commence work before this checkpoint; and If necessary, specify the RRM requirements [RAN4] related to the above objectives.

[0065] The general consensus is that in conditional L1 / L2 triggered mobility (LTM), as in regular conditional handover (CHO), the network configures the conditions for UE evaluation (e.g., based on L1 measurements). Once the configured conditions evaluated by the UE are met, the UE will perform LTM. However, the detailed signaling for such conditional LTM is unclear from known solutions. For example, it is currently unknown or undefined what the conditions should be, in which signal such condition configuration should be provided, or what the expected behavior of the UE might be. Furthermore, resources for the target cell (e.g., RACH or configured authorization) are included in the RRC reconfiguration message (i.e., ... Figure 9 In step 2), these resources are allocated. Since these resources are pre-allocated to multiple candidate cells, there is a problem of resource waste (i.e., resources that are allocated but ultimately not used) even if the UE does not eventually hand over to those candidate cells and therefore does not use such resources.

[0066] Therefore, the problems to be addressed by conditional LTM include how to minimize resource consumption, how such conditional LTM commands and their conditions should be signaled, and how the UE should be configured to act accordingly upon receiving a conditional LTM command. Embodiments of this disclosure seek to provide solutions to these problems.

[0067] Conditional LTM command

[0068] Figure 10 The diagram illustrates partial schematics and partial message flow diagrams of a wireless communication system according to at least some embodiments of the present technology. The wireless communication system includes a source infrastructure device (e.g., gNB) 110, a target infrastructure device (e.g., gNB) 120, and a communication device 100 (e.g., UE). Each of the communication device 100, source infrastructure device 110, and target infrastructure device 120 includes transceivers (or transceiver circuits) 101, 111, 121 and controllers (or controller circuits) 102, 112, 122. Each of the controllers 102, 112, 122 may be, for example, a microprocessor, CPU, or dedicated chipset. Controllers 102, 112, 122 may also each be equipped with a memory unit (…). Figure 10 (Not shown in the image). The communication device 100 is initially connected to the source infrastructure device 110, which operates the serving cell within the coverage area of ​​the communication device 100. Therefore, the transceiver circuit 101 and controller circuit 102 of the communication device 100 can be (initially) configured to send 131 signals to and / or receive 131 signals from the source infrastructure device 110.

[0069] like Figure 10As illustrated in the example, the transceiver circuitry 101 and controller circuitry 102 of the communication device 100 are configured to receive one or more conditional lower-layer triggered mobility (LTM) handover commands from a source infrastructure device 110 (to which the communication device 100 is connected). Each conditional LTM handover command 132 includes an indication to at least one target infrastructure device (e.g., target infrastructure device 120) and an indication of one or more conditions, which, if satisfied, will cause the communication device 100 to perform an LTM handover process to switch from the source infrastructure device 110 to the target infrastructure device 120. Here, the LTM handover process consists only of signaling at the physical layer at each of the source infrastructure device 110, the target infrastructure device 120, and the communication device 100, and / or signaling at the data link layer (e.g., the media access control (MAC) layer) at each of the source infrastructure device 110, the target infrastructure device 120, and the communication device 100.

[0070] Subsequently, the transceiver circuit 101 and controller circuit 102 of communication device 100 may be further configured to determine that one or more conditions indicated by one of the received conditional LTM handover commands 132 have been met, and 134 execute an LTM handover process to switch communication device 100 from source infrastructure device 110 to target infrastructure device 120 indicated by the received conditional LTM handover command 132, wherein communication device 100 determines that one or more conditions have been met in response to the command. After this, communication device 100 is now connected to target infrastructure device 120, and therefore the transceiver circuit 101 and controller circuit 102 of communication device 100 may be configured to send a 135 signal to and / or receive a 135 signal from target infrastructure device 120.

[0071] In the Figure 9In an example implementation of this technology, communication device 100 may receive a conditional LTM handover command 132, wherein such conditional LTM handover command 132 may indicate a single target infrastructure device 120 and one(or more) conditional handover conditions associated with that single target infrastructure device 120. Alternatively, the single conditional LTM handover command 132 may indicate multiple target infrastructure devices and one(or more) conditional handover conditions associated with each of these target infrastructure devices (wherein the conditions may differ for different target infrastructure devices (e.g., different values / thresholds / offsets or different numbers of conditions to be satisfied)). Alternatively, communication device 100 may receive multiple conditional LTM handover commands 132, wherein each conditional LTM handover command 132 includes an indication of a target infrastructure device and its associated conditional handover conditions, or multiple target infrastructure devices and their associated conditional handover conditions. When the communication device 100 receives multiple conditional LTM handover commands 132, each conditional LTM handover command 132 may indicate a different number of target infrastructure devices and / or conditions between them.

[0072] Here, "target infrastructure equipment" or "candidate infrastructure equipment" is used interchangeably with "target cell" or "candidate cell". Those skilled in the art will understand that these terms can be understood to refer essentially to the same thing, or more specifically, a "target / candidate cell" is a cell controlled by the "target / candidate infrastructure equipment". Similarly, "source infrastructure equipment" or "serving infrastructure equipment" is also used interchangeably with "source cell" or "serving cell" (or refers to the infrastructure equipment / gNB that controls the "source cell" or "serving cell").

[0073] Basically, such as Figure 10 Some embodiments of this technology illustrated propose that the UE receives an LTM command (or multiple LTM commands) containing an indication of conditions to be evaluated by the UE. Here, if (and when) these conditions are met, the UE will then execute an LTM cell handover command for a specific target cell indicated in the LTM command and associated with these conditions.

[0074] In this scenario, the UE can receive one or more conditional LTM cell handover commands for one or more target cells within a single MAC control element (MAC CE) or separate MAC CEs. In other words, the communication device can be configured to receive a MAC CE from the source infrastructure equipment, where the MAC CE includes all or all of the one or more conditional LTM handover commands. Alternatively, the communication device can be configured to receive one or more MAC CEs from the source infrastructure equipment, where each MAC CE includes one conditional LTM handover command from the one or more conditional LTM handover commands.

[0075] In some arrangements of this technical implementation, one or more conditions may include event A3, but specifically, when the measurement performed at the physical layer (i.e., L1 measurement) of the target candidate cell becomes an offset better than the L1 measurement of the serving cell. In other words, one or more conditions may include the quality of the physical layer signal received from the target infrastructure equipment being at least a predetermined amount higher than the quality of the physical layer signal received from the source infrastructure equipment.

[0076] Alternatively, or additionally, in some arrangements of embodiments of this technology, one or more conditions may include event A4, but specifically, when the measurement performed at the physical layer (i.e., L1 measurement) of the target candidate cell becomes better than a set threshold amount. In other words, one or more conditions may include the quality of the physical layer signal received from the target infrastructure equipment being higher than a predetermined threshold.

[0077] Alternatively, or additionally, in some arrangements of embodiments of this technology, one or more conditions may include event A5, but specifically, when the measurement performed at the physical layer (i.e., L1 measurement) of the target candidate cell becomes better than a set threshold amount, while the measurement performed at the physical layer (i.e., L1 measurement) of the serving cell becomes worse than the set threshold amount. In other words, one or more conditions may include the quality of the physical layer signal received from the source infrastructure equipment being lower than a predetermined threshold, and the quality of the physical layer signal received from the target infrastructure equipment being higher than the predetermined threshold.

[0078] Overall, the process proposed in the arrangement of the embodiments of this technology disclosed herein is consistent with the above description and as follows. Figure 9 The traditional LTM signaling process shown is basically the same. However, this technical implementation proposes to... Figure 9 The process is modified to enable the configuration of conditional LTM handover for the UE, and this is achieved by including an indication in the LTM cell handover command that specifies one or more conditions to be met before the LTM handover is triggered.

[0079] Figure 11 The example message flow diagram illustrates this, in which Figure 9 The LTM cell handover command in step 6 of the illustrated process is modified 141 to include some conditions that the UE will evaluate before executing the cell handover command. Furthermore, as described above, in step 6, the UE may receive one or more LTM commands 141 in a single message (MAC CE) or separately (in multiple MAC CEs) to evaluate 142 whether these conditions are met for each of the multiple target cells. It should be noted that although the UE can evaluate 142 conditions for each cell, the UE will ultimately only hand over to one cell at the end of the LTM handover process. The target cell that the UE ultimately hands over to can be the target cell whose associated conditions are first met, or it can be the target cell with the highest signal quality (e.g., RSRP, RSRQ, SINR) when the conditions of multiple target cells are met.

[0080] In the current LTM process (e.g., Figure 9 As shown), the resources of the target cell (e.g., RACH, configured authorization) are allocated in the RRC reconfiguration message (i.e., as described above). Figure 9 (In step 2). For example, to enable the UE to hand over to the target cell, the UE should send a RACH preamble to the target cell, and the RACH resources used to send this preamble can be pre-allocated for each candidate target cell based on contention-free random access (CFRA) to determine the timing advance. Otherwise, the UE should use contention-based RACH transmission to determine the timing advance.

[0081] Furthermore, in RACH-free scenarios where the UE has a known timing advance (e.g., a small cell with TA=0, or a scenario where the UE derives TA based on the timing difference between the serving cell and the target cell), the UE utilizes the configured grant (CG) resources to send the first message (e.g., data) to indicate its arrival at the target cell. During the current LTM process, the CG resources are... Figure 9 In step 2, resources are pre-allocated for each target cell. However, in this case—as in the RACH scenario above—only the resources of the target cell to which the UE ultimately hands over will be used, while the resources allocated for all other candidate target cells will be wasted.

[0082] Therefore, in some arrangements of the embodiments of this technology, such as Figure 12 As shown in the example flowchart, to minimize resource consumption, only for the target cell included in the LTM cell handover command 141 (which includes the conditions for the UE to evaluate 142 for the indicated target cell), in ( Figure 9Resource 143 is allocated between steps 5 and 6 of the existing LTM process shown. It should be noted that resource allocation is exchanged between the serving cell and the target cell before the source cell sends an LTM cell handover command 141 to the UE. In other words, the communication device can be configured to send a measurement report to the source infrastructure device before receiving one or more conditional LTM handover commands. This measurement report includes an indication of measurements performed by the communication device on physical layer signals received from one or more candidate infrastructure devices, which are candidates for at least one target infrastructure device indicated by each of the one or more conditional LTM handover commands. The communication device is also configured to receive, after sending the measurement report and before receiving the one or more conditional LTM handover commands, radio resources allocated from the source infrastructure device for each of the at least one target infrastructure device indicated by each of the one or more conditional LTM handover commands (i.e., for the communication device to send initial signals during the handover process).

[0083] In some arrangements of the embodiments of this technology, such as Figure 12 As shown, it is not as defined by the arrangement of the paragraphs above ( Figure 9 Instead of allocating resources between steps 5 and 6 in the existing LTM process, resources are allocated in (…). Figure 9 The resources allocated in step 2 of the existing LTM process are deallocated (i.e. released) between steps 5 and 6 for a target cell not included in the LTM cell handover command 141. In other words, the communication device can be configured to receive a Radio Resource Control (RRC) configuration message from a source infrastructure device before receiving one or more conditional LTM handover commands. This message includes radio resources allocated for each of one or more candidate infrastructure devices (i.e., for the communication device to send an initial signal during the handover process), the one or more candidate infrastructure devices being candidates for at least one target infrastructure device indicated by each of the one or more conditional LTM handover commands. The device is also configured to, after receiving the RRC configuration message and before receiving the one or more conditional LTM handover commands, send a measurement report to the source infrastructure device. This measurement report includes an indication of measurements performed by the communication device on physical layer signals received from the one or more candidate infrastructure devices. Furthermore, the device is configured to, after sending the measurement report and before receiving (or during) receiving the one or more conditional LTM handover commands, receive an indication from the source infrastructure device that the radio resources allocated by the RRC configuration message for the candidate infrastructure devices not among the at least one target infrastructure devices indicated by each of the one or more conditional LTM handover commands are released.

[0084] In addition to indicating to the UE that the resources have been released (or separately), these resources can also be released by the source cell in the candidate cell itself (not in the target cell indicated in the LTM command). In other words, the source infrastructure device can be configured to send a Radio Resource Control (RRC) configuration message to a communication device before sending one or more conditional LTM handover commands. This message includes radio resources allocated to each of one or more candidate infrastructure devices, which are candidates for at least one target infrastructure device indicated by each of the one or more conditional LTM handover commands. The source infrastructure device is also configured to receive a measurement report from the communication device after sending the RRC configuration message and before sending the one or more conditional LTM handover commands. This measurement report includes an indication from the communication device of measurements performed on physical layer signals received from the one or more candidate infrastructure devices. Furthermore, the source infrastructure device is configured to send an indication, after receiving the measurement report and before sending the one or more conditional LTM handover commands, to the candidate infrastructure devices not among the at least one target infrastructure devices indicated by each of the one or more conditional LTM handover commands. This indication indicates that the radio resources allocated by the RRC configuration message to the candidate infrastructure devices not among the at least one target infrastructure devices indicated by each of the one or more conditional LTM handover commands are released.

[0085] In some implementations of this technology, when a target cell allocates resources, a timer is used to indicate how long these resources will be held, and the target cell releases these resources if the timer expires. This reduces resource waste, but does impose a limitation on the time it takes for the UE to assess handover conditions and execute a handover command when those conditions are met. In other words, the communication device can be configured to receive an RRC configuration message from a source infrastructure device before receiving one or more conditional LTM handover commands. This message includes radio resources allocated for each of one or more candidate infrastructure devices, which are candidates for at least one target infrastructure device indicated by each of the one or more conditional LTM handover commands, and is configured to determine that the radio resources allocated by the RRC configuration message will be released after a predetermined time period (i.e., as configured by the timer). Here, the predetermined time period (configured by the timer) can begin when the communication device receives (or sends out) at least one of the one or more conditional LTM handover commands.

[0086] Here, the timer value can be included in the LTM cell handover command (i.e., associated with the resources of the target cell indicated in the LTM cell handover command), allowing the UE to know after which the resources of the target cell will be released. Alternatively, the timer can be configured by an RRC message (i.e., received from the source cell) but started when the UE receives the LTM cell handover command. Alternatively, the timer can be configured by an RRC message or an LTM handover command but can start when the UE receives a physical layer signaling message (e.g., DCI) from the source cell.

[0087] Multiple timers can be configured, each associated with one of the target cell / target infrastructure devices. When multiple timers are configured, these timers can have different lengths / time periods, for example, based on the priority of the specific target cell for which the timer is configured, the current or expected service load, or some other parameter.

[0088] In some arrangements of the embodiments of this technology, such as Figure 12 As shown, the arrangement is not as defined in the paragraphs above. Figure 9 The existing LTM process (shown) allocates or releases resources between steps 5 and 6, but when the target cell is in ( Figure 9In step 2 of the existing LTM procedure shown, when resources are allocated, these resources are deactivated by default, and then activated 143 before the network sends an LTM cell handover command 141 for a specific target cell. It should be noted that this activation occurs between the serving cell and the target cell before the source cell sends the LTM cell handover command 141 to the UE. In other words, the communication device can be configured to receive an RRC configuration message from a source infrastructure device before receiving one or more conditional LTM handover commands. This message includes radio resources allocated for each of one or more candidate infrastructure devices (i.e., for the communication device to send initial signals during the handover process). The one or more candidate infrastructure devices are candidates for at least one target infrastructure device indicated by each of the one or more conditional LTM handover commands, wherein the allocated radio resources are deactivated. The device is also configured to send a measurement report to the source infrastructure device after receiving the RRC configuration message and before receiving the one or more conditional LTM handover commands. This measurement report includes an indication of measurements performed by the communication device on physical layer signals received from the one or more candidate infrastructure devices. Furthermore, the device is configured to receive an indication from the source infrastructure device after sending the measurement report and before receiving the one or more conditional LTM handover commands, indicating that the radio resources allocated by the RRC configuration message for the candidate infrastructure devices among the at least one target infrastructure devices indicated by each of the one or more conditional LTM handover commands are activated. Here, for the resources of the target cell that are not included in the LTM cell handover command 141 and are therefore not activated 143 (allocated but deactivated), the resources of the target cell that are included in the LTM cell handover command 141 and are thus activated 143 can be explicitly deallocated or released 143 when (or close to) when the resources are activated.

[0089] Here, the indication that the radio resources allocated to a candidate infrastructure device among at least one target infrastructure device indicated by one or more conditional LTM handover commands are activated by the RRC configuration message can be received within the conditional LTM handover command, rather than as a separate indication. In other words, the communication device can be configured to: receive an RRC configuration message from a source infrastructure device before receiving one or more conditional LTM handover commands, the RRC configuration message including radio resources allocated to each of one or more candidate infrastructure devices, which are candidates for at least one target infrastructure device indicated by one or more conditional LTM handover commands, wherein the allocated radio resources are deactivated; and after receiving the RRC configuration message and before receiving one or more conditional LTM handover commands, send a measurement report to the source infrastructure device, the measurement report including an indication of measurements performed by the communication device on physical layer signals received from the one or more candidate infrastructure devices; wherein each of the one or more conditional LTM handover commands includes an indication that the radio resources allocated by the RRC configuration message to a candidate infrastructure device of one of the at least one target infrastructure devices indicated by the conditional LTM handover command have been activated. The indication that the resources of the target infrastructure device included in the conditional LTM handover command have been activated can be an explicit indication that such resources have been activated. Alternatively, the activation can be implicit, and the UE can assume that the resources are automatically activated based on the fact that the cell ID of the target cell (for which these resources are allocated in the RRC configuration message) is included in the LTM cell command.

[0090] Here, such an instruction can have a build-release structure. That is, as described above, the target cell in step 2 ( Figure 9 Resources are allocated in the existing LTM procedure (as shown), and these resources are deactivated by default. For example, resources can be allocated for a configuration of five candidate cells, each associated with an index indicated by the RRC configuration message in step 2. Subsequently, the conditional LTM handover command can indicate the index of the target cell / resource that is being activated—for example, it can indicate the indices of three candidate cells, which the UE then understands as the LTM target cells for which it needs to evaluate the conditions. Here, for other indices that are not indicated (such as the other two candidate cells in this example), the resources allocated in the RRC configuration message can be implicitly released, or the conditional LTM handover command (or some other downlink message) can explicitly indicate that these resources are released.

[0091] Currently in version 18, the maximum number of target cells that can be configured for LTM is eight, while the maximum number of target cells that can be indicated in an LTM command is one. This means that only one cell can be indicated for handover at a given time. As mentioned above, the UE can receive conditional LTM commands indicating multiple target cells, or it can receive multiple conditional LTM commands, each indicating one or more target cells. Thus, limiting the maximum number of target cells that can be indicated in an LTM command to one is relatively inflexible. In cases where multiple target cells exist where the LTM handover conditions are likely to be met, only one possible target cell is provided to the UE. Indicating multiple target cells in an LTM command increases the likelihood that the UE will determine if the conditions for a particular target cell are met, thereby enabling earlier and more efficient LTM handover (because the UE's communication session can continue, and resources of other non-required cells can be released or allocated earlier).

[0092] In some implementations of this technology, the maximum number of target cells that can be indicated in the LTM command used to evaluate conditions can be set to greater than one (e.g., two, three, four, five, etc.) to provide the UE with the flexibility to determine conditions for multiple potential target UEs, but less than the maximum number of target cells that can be configured for LTM (eight), to reduce the amount of measurement and evaluation that the UE needs to perform and the amount of resources that need to be allocated, activated, or otherwise held for the UE for LTM handover. In other words, the communication device can be configured to receive an RRC configuration message from a source infrastructure device before receiving one or more conditional LTM handover commands. The RRC configuration message includes an indication of one or more candidate infrastructure devices, which are candidates for at least one target infrastructure device indicated by each of the one or more conditional LTM handover commands, wherein the maximum number of target infrastructure devices that can be indicated by the one or more conditional LTM handover commands is less than the maximum number of candidate infrastructure devices that can be indicated by the RRC configuration message.

[0093] In some implementations of this technology, to reduce the complexity of UE management of candidate cells, if the UE sends an L1 measurement report (such as...) Figure 9 After step 5 of the existing LTM process shown, the downlink and uplink (e.g., ...) are executed synchronously. Figure 9 As shown in steps 4a and 4b of the existing LTM process, this can significantly reduce the number of candidate cells. This is because, as... Figure 9 Compared to the L3 measurement performed in step 1 of the existing LTM procedure, the L1 measurement report presents the most reliable target cell for handover.

[0094] Therefore, in such arrangements of embodiments of this technology, as Figure 13As shown in the example flowchart, downlink synchronization 144 and uplink synchronization 145 with candidate target cells (e.g.) Figure 9 The steps (currently performed in steps 4a and 4b of the existing LTM process) should be performed after step 5; that is, after sending the L1 measurement report but before receiving the LTM cell handover command 141. In other words, the communication device can be configured to: send a measurement report to a source infrastructure device before receiving one or more conditional LTM handover commands, the measurement report including an indication of measurements performed by the communication device on physical layer signals received from one or more candidate infrastructure devices, the one or more candidate infrastructure devices being candidates for at least one target infrastructure device indicated by each of the one or more conditional LTM handover commands; and perform downlink and / or uplink synchronization with one or more candidate infrastructure devices based on commands received from the source infrastructure device after sending the measurement report. However, those skilled in the art should understand that this arrangement of such embodiments of the present technology does not imply that L3 measurement is unnecessary.

[0095] Those skilled in the art should understand that Figure 11 , Figure 12 and Figure 13 The method flowchart shown and Figure 10 The schematic diagrams and message flow diagrams provided can be adapted to the implementation of this technology. For example, such methods may include other intermediate steps, or these steps may be executed in any logical order. Although the implementation of this technology is mainly through... Figure 10 The exemplary communication systems shown are described herein, but those skilled in the art will understand that they can be applied equally to other systems described herein.

[0096] Those skilled in the art should further understand that the infrastructure equipment and / or communication devices thus defined can be further limited according to the various arrangements and implementations discussed in the preceding paragraphs. Those skilled in the art should also further understand that the infrastructure equipment and communication devices thus defined and described can constitute part of other communication systems besides the communication system defined in this disclosure.

[0097] The following numbered paragraphs provide further exemplary aspects and features of this technology: Paragraph 1. A method of operating a communication device, the method comprising: The communication device receives one or more conditional lower-layer triggered mobility LTM handover commands from its connected source infrastructure equipment. Each conditional LTM handover command includes an indication to at least one target infrastructure equipment and an indication to one or more conditions. If one or more conditions are met, the communication device performs an LTM handover procedure to switch from the source infrastructure equipment to the target infrastructure equipment. The LTM handover process consists only of signaling at the physical layer and / or the media access control (MAC) layer at each of the source infrastructure device, target infrastructure device, and communication device.

[0098] Paragraph 2. Based on the method in paragraph 1, including: It is determined that one or more conditions indicated by one of the received conditional LTM handover commands are met, and The LTM handover procedure is performed to switch from the source infrastructure device to the target infrastructure device indicated by the received conditional LTM handover command, where one or more conditions are determined to be met.

[0099] Paragraph 3. According to the method of paragraph 1 or paragraph 2, one or more of the conditions include that the quality of the physical layer signal received from the target infrastructure device is greater than the quality of the physical layer signal received from the source infrastructure device by at least a predetermined amount.

[0100] Paragraph 4. According to any one of paragraphs 1 to 3, one or more of the conditions include that the quality of the physical layer signal received from the target infrastructure device is greater than a predetermined threshold.

[0101] Paragraph 5. The method according to any one of paragraphs 1 to 4, wherein one or more conditions include the quality of the physical layer signal received from the source infrastructure device being less than a predetermined threshold, and the quality of the physical layer signal received from the target infrastructure device being greater than the predetermined threshold.

[0102] Paragraph 6. Using any of the methods described in paragraphs 1 through 5, including: Receive MAC control element CE from source infrastructure equipment, wherein the MAC CE includes all of one or more conditional LTM switching commands.

[0103] Paragraph 7. Using any of the methods described in paragraphs 1 through 6, including: Receive one or more MAC CEs from the source infrastructure device, wherein each of the MAC CEs includes one of one or more conditional LTM handover commands.

[0104] Paragraph 8. Based on any of the methods in paragraphs 1 through 7, including: Before receiving one or more conditional LTM handover commands, a measurement report is sent to the source infrastructure device. This measurement report includes indications of measurements performed by the communication device on physical layer signals received from one or more candidate infrastructure devices, where the candidate infrastructure devices are candidates for at least one target infrastructure device indicated by each of the one or more conditional LTM handover commands. After sending a measurement report and before receiving one or more conditional LTM handover commands, the allocation of radio resources from the source infrastructure device to each of at least one target infrastructure device indicated by the one or more conditional LTM handover commands is received.

[0105] Paragraph 9. Using any of the methods described in paragraphs 1 through 8, including: Before receiving one or more conditional LTM handover commands, a Radio Resource Control (RRC) configuration message is received from the source infrastructure device. This RRC configuration message includes the allocation of radio resources for each of one or more candidate infrastructure devices, which are candidates for at least one target infrastructure device indicated by each of the one or more conditional LTM handover commands. After receiving the RRC configuration message and before receiving one or more conditional LTM handover commands, a measurement report is sent to the source infrastructure device. This measurement report includes indications of measurements performed by the communication device on physical layer signals received from one or more candidate infrastructure devices. After sending the measurement report and before receiving one or more conditional LTM handover commands, the following indication is received from the source infrastructure device: the radio resources allocated by the RRC configuration message to the candidate infrastructure device that is not one of the at least one target infrastructure device indicated by the one or more conditional LTM handover commands are released.

[0106] Paragraph 10. According to any one of the methods in paragraphs 1 through 9, including: Before receiving one or more conditional LTM handover commands, an RRC configuration message is received from the source infrastructure device. This RRC configuration message includes the allocation of radio resources for each of one or more candidate infrastructure devices, which are candidates for at least one target infrastructure device indicated by each of the one or more conditional LTM handover commands. It is determined that the radio resources allocated by the RRC configuration message will be released after a predetermined time period.

[0107] Paragraph 11. According to the method of paragraph 10, the predetermined time period begins when the communication device receives at least one of the conditional LTM handover commands.

[0108] Paragraph 12. According to the method of paragraph 10 or paragraph 11, wherein the predetermined time period begins when the communication device receives a physical layer signaling message from the source infrastructure equipment.

[0109] Paragraph 13. The method according to any one of paragraphs 10 to 12, wherein the predetermined time period is indicated in at least one conditional LTM switching command.

[0110] Paragraph 14. The method according to any one of paragraphs 10 to 13 includes: receiving an RRC message from a source infrastructure device that includes an indication of a predetermined time period.

[0111] Paragraph 15. Using any of the methods described in paragraphs 1 through 14, including: Before receiving one or more conditional LTM handover commands, an RRC configuration message is received from the source infrastructure device. The RRC configuration message includes radio resource allocation for each of one or more candidate infrastructure devices, which are candidates for at least one target infrastructure device indicated by each of the one or more conditional LTM handover commands, wherein the allocated radio resources are deactivated. After receiving the RRC configuration message and before receiving one or more conditional LTM handover commands, a measurement report is sent to the source infrastructure device. This measurement report includes an indication of measurements performed by the communication device on physical layer signals received from one or more candidate infrastructure devices; and After sending the measurement report and before receiving one or more conditional LTM handover commands, the following indication is received from the source infrastructure device: the radio resources allocated to the candidate infrastructure device in at least one target infrastructure device indicated by the RRC configuration message for each of the one or more conditional LTM handover commands are activated.

[0112] Paragraph 16. Using any of the methods described in paragraphs 1 through 15, including: Before receiving one or more conditional LTM handover commands, an RRC configuration message is received from the source infrastructure device. The RRC configuration message includes the allocation of radio resources for each of one or more candidate infrastructure devices, which are candidates for at least one target infrastructure device indicated by each of the one or more conditional LTM handover commands, wherein the allocated radio resources are deactivated. After receiving the RRC configuration message and before receiving one or more conditional LTM handover commands, a measurement report is sent to the source infrastructure device. The measurement report includes an indication of measurements performed by the communication device on physical layer signals received from one or more candidate infrastructure devices. Each of one or more conditional LTM handover commands includes the following indication: the radio resources allocated by the RRC configuration message to the candidate infrastructure device in at least one target infrastructure device indicated by the conditional LTM handover command are activated.

[0113] Paragraph 17. Using any of the methods described in paragraphs 1 through 16, including: Before receiving one or more conditional LTM handover commands, an RRC configuration message is received from the source infrastructure device. The RRC configuration message includes an indication of one or more candidate infrastructure devices, which are candidates for at least one target infrastructure device indicated by each of the one or more conditional LTM handover commands. The maximum number of target infrastructure devices that one or more conditional LTM switching commands can indicate is less than the maximum number of candidate infrastructure devices that the RRC configuration message can indicate.

[0114] Paragraph 18. According to any one of the methods in paragraphs 1 through 17, including: Before receiving one or more conditional LTM handover commands, a measurement report is sent to the source infrastructure device. This measurement report includes indications of measurements performed by the communication device on physical layer signals received from one or more candidate infrastructure devices, which are candidates for at least one target infrastructure device indicated by each of the one or more conditional LTM handover commands; and After sending the measurement report, synchronization is performed in the downlink and / or uplink with one or more of the candidate infrastructure devices based on commands received from the source infrastructure device.

[0115] Paragraph 19. A communication device, comprising: Transceiver circuitry, configured to transmit and / or receive signals; and The controller circuit is configured to be combined with the transceiver circuit. The communication device receives one or more conditional low-level triggered mobility LTM handover commands from a source infrastructure device to which it is connected, wherein each conditional LTM handover command includes an indication to at least one target infrastructure device and an indication to one or more conditions, and if one or more conditions are met, the communication device will perform an LTM handover process to switch from the source infrastructure device to the target infrastructure device. The LTM handover process consists only of signaling at the physical layer and / or the media access control (MAC) layer at each of the source infrastructure device, target infrastructure device, and communication device.

[0116] Paragraph 20. A circuit for a communication device, the circuit comprising: Transceiver circuitry, configured to transmit and / or receive signals; and The controller circuit is configured to be combined with the transceiver circuit. The communication device receives one or more conditional low-level triggered mobility LTM handover commands from a source infrastructure device to which it is connected, wherein each conditional LTM handover command includes an indication to at least one target infrastructure device and an indication to one or more conditions, and if one or more conditions are met, the communication device will perform an LTM handover process to switch from the source infrastructure device to the target infrastructure device. The LTM handover process consists only of signaling at the physical layer and / or the media access control (MAC) layer at each of the source infrastructure device, target infrastructure device, and communication device.

[0117] Paragraph 21. A method for operating infrastructure equipment of a wireless communication network, the infrastructure equipment being a source infrastructure equipment to which a communication device is connected, the method comprising: Send one or more conditional low-level triggered mobility LTM handover commands to the communication device, wherein each conditional LTM handover command includes an indication to at least one target infrastructure device and an indication to one or more conditions, and if one or more conditions are met, the communication device will perform an LTM handover procedure to switch from the infrastructure device to the target infrastructure device. The LTM handover process consists only of signaling at the physical layer and / or the Media Access Control (MAC) layer at each of the infrastructure equipment, target infrastructure equipment, and communication devices.

[0118] Paragraph 22. According to the method of paragraph 21, one or more conditions include: the quality of the physical layer signal received by the communication device from the target infrastructure equipment is at least a predetermined amount higher than the quality of the physical layer signal transmitted by the infrastructure equipment to the communication device.

[0119] Paragraph 23. According to the method of paragraph 21 or paragraph 22, one or more conditions include: the quality of the physical layer signal received by the communication device from the target infrastructure equipment is higher than a predetermined threshold.

[0120] Paragraph 24. The method according to any one of paragraphs 21 to 23, wherein one or more conditions include: the quality of the physical layer signal transmitted by the infrastructure equipment to the communication device is lower than a predetermined threshold, and the quality of the physical layer signal received by the communication device from the target infrastructure equipment is higher than the predetermined threshold.

[0121] Paragraph 25. According to any one of the methods in paragraphs 21 through 24, including: Send a Media Access Control (MAC) control element (CE) to the communication device, wherein the MAC CE includes all of one or more conditional LTM switching commands.

[0122] Paragraph 26. According to any one of the methods in paragraphs 21 through 25, including: Send one or more MAC CEs to the communication device, wherein each MAC CE includes one of one or more conditional LTM switching commands.

[0123] Paragraph 27. According to any one of the methods in paragraphs 21 to 26, including: Before sending one or more conditional LTM handover commands, a measurement report is received from the communication device, the measurement report including indications of measurements performed by the communication device on physical layer signals received from one or more candidate infrastructure devices, the one or more candidate infrastructure devices being candidates for at least one target infrastructure device indicated by each of the one or more conditional LTM handover commands; and After receiving the measurement report and before sending one or more conditional LTM handover commands, the radio resource allocation for each of at least one target infrastructure device indicated by each of the one or more conditional LTM handover commands is sent to the communication device.

[0124] Paragraph 28. According to any one of the methods in paragraphs 21 to 27, including: Before sending one or more conditional LTM handover commands, a radio resource control (RRC) configuration message is sent to the communication device. The RRC configuration message includes the allocation of radio resources for each of one or more candidate infrastructure devices, which are candidates for at least one target infrastructure device indicated by each of the one or more conditional LTM handover commands. After sending the RRC configuration message and before sending one or more conditional LTM handover commands, a measurement report is received from the communication device, the measurement report including an indication of measurements performed by the communication device on physical layer signals received from one or more candidate infrastructure devices; and Upon receiving the measurement report and before sending one or more conditional LTM handover commands, the following instruction is sent to the communication device: the radio resources allocated by the RRC configuration message to the candidate infrastructure device in at least one target infrastructure device not indicated in each of the one or more conditional LTM handover commands are released.

[0125] Paragraph 29. According to any one of the methods in paragraphs 21 to 28, including: Before sending one or more conditional LTM handover commands, a radio resource control (RRC) configuration message is sent to the communication device. The RRC configuration message includes the allocation of radio resources for each of one or more candidate infrastructure devices, which are candidates for at least one target infrastructure device indicated by each of the one or more conditional LTM handover commands. After sending the RRC configuration message and before sending one or more conditional LTM handover commands, a measurement report is received from the communication device, the measurement report including an indication of measurements performed by the communication device on physical layer signals received from one or more candidate infrastructure devices; and Upon receiving the measurement report and before sending one or more conditional LTM handover commands, the following instruction is sent to a candidate infrastructure device in at least one target infrastructure device not indicated in each of the one or more conditional LTM handover commands: the radio resources allocated by the RRC configuration message to the candidate infrastructure device in at least one target infrastructure device not indicated in each of the one or more conditional LTM handover commands are released.

[0126] Paragraph 30. According to any one of the methods in paragraphs 21 through 29, including: Before sending one or more conditional LTM handover commands, an RRC configuration message is sent to the communication device, the RRC configuration message including the allocation of radio resources for each of one or more candidate infrastructure devices, the one or more candidate infrastructure devices being candidates for at least one target infrastructure device indicated by each of the one or more conditional LTM handover commands; The radio resources allocated by the RRC configuration message will be released after a predetermined time period.

[0127] Paragraph 31. According to the method of paragraph 30, the predetermined time period begins when the communication device receives at least one of one or more conditional LTM handover commands.

[0128] Paragraph 32. According to the method of paragraph 30 or paragraph 31, the predetermined time period begins when the communication device receives a physical layer signaling message from the infrastructure equipment.

[0129] Paragraph 33. The method according to any one of paragraphs 30 to 32, wherein the predetermined time period is indicated in at least one conditional LTM switching command.

[0130] Paragraph 34. According to any one of the methods in paragraphs 30 to 33, including: Send an RRC message to the communication device, including an indication of a predetermined time period.

[0131] Paragraph 35. According to any one of the methods in paragraphs 21 to 34, including

[0132] Before sending one or more conditional LTM handover commands, an RRC configuration message is sent to the communication device. This RRC configuration message includes the allocation of radio resources for each of one or more candidate infrastructure devices, which are candidates for at least one target infrastructure device indicated by each of the one or more conditional LTM handover commands, wherein the allocated radio resources are deactivated. After sending the RRC configuration message and before sending one or more conditional LTM handover commands, a measurement report is received from the communication device. This measurement report includes an indication of measurements performed by the communication device on physical layer signals received from one or more candidate infrastructure devices. After receiving the measurement report and before sending one or more conditional LTM handover commands, an instruction is sent to the communication device indicating that the radio resources allocated to the candidate infrastructure device in at least one target infrastructure device indicated by the RRC configuration message in each of the one or more conditional LTM handover commands are activated.

[0133] Paragraph 36. According to any one of the methods in paragraphs 21 to 35, including

[0134] Before sending one or more conditional LTM handover commands, an RRC configuration message is sent to the communication device. This RRC configuration message includes the allocation of radio resources for each of one or more candidate infrastructure devices, which are candidates for at least one target infrastructure device indicated by each of the one or more conditional LTM handover commands, wherein the allocated radio resources are deactivated. After sending the RRC configuration message and before sending one or more conditional LTM handover commands, a measurement report is received from the communication device. This measurement report includes indications of measurements performed by the communication device on physical layer signals received from one or more candidate infrastructure devices. Each of the one or more conditional LTM handover commands includes an indication that the radio resources allocated by the RRC configuration message for a candidate infrastructure device in at least one target infrastructure device indicated by the conditional LTM handover command are activated.

[0135] Paragraph 37. According to any one of the methods in paragraphs 21 to 36, including

[0136] Before sending one or more conditional LTM handover commands, an RRC configuration message is sent to the communication device. This RRC configuration message includes indications of one or more candidate infrastructure devices, which are candidates for at least one target infrastructure device indicated by each of the one or more conditional LTM handover commands. Among them, the maximum number of target infrastructure devices that one or more conditional LTM handover commands can indicate is less than the maximum number of candidate infrastructure devices that RRC configuration messages can indicate.

[0137] Paragraph 38. According to any one of the methods in paragraphs 21 to 37, including

[0138] Before sending one or more conditional LTM handover commands, a measurement report is received from the communication device. This measurement report includes indications of measurements performed by the communication device on physical layer signals received from one or more candidate infrastructure devices, where the one or more candidate infrastructure devices are candidates for at least one target infrastructure device indicated by each of the one or more conditional LTM handover commands.

[0139] After receiving the measurement report, commands are sent to the communication device to perform synchronization with one or more candidate infrastructure devices in the downlink and / or uplink.

[0140] Paragraph 39. An infrastructure device for a wireless communication network, the infrastructure device being a source infrastructure device to which a communication device is connected, the infrastructure device comprising:

[0141] The transceiver circuitry is configured to transmit and / or receive signals, and

[0142] The controller circuit is configured to be combined with the transceiver circuit. The system sends one or more conditional low-level triggered mobility LTM handover commands to a communication device, wherein each conditional LTM handover command includes an indication of at least one target infrastructure device and an indication of one or more conditions. If these conditions are met, the communication device performs an LTM handover procedure to switch from the infrastructure device to the target infrastructure device. The LTM handover process consists only of signaling at the physical layer and / or the media access control (MAC) layer at each of the infrastructure equipment, target infrastructure equipment, and communication devices.

[0143] Paragraph 40. A circuit for an infrastructure device in a wireless communication network, the infrastructure device being a source infrastructure device to which a communication device is connected, the circuit comprising:

[0144] The transceiver circuitry is configured to transmit and / or receive signals, and

[0145] The controller circuit is configured to be combined with the transceiver circuit. The system sends one or more conditional low-level triggered mobility LTM handover commands to a communication device, wherein each conditional LTM handover command includes an indication of at least one target infrastructure device and an indication of one or more conditions. If these conditions are met, the communication device performs an LTM handover procedure to switch from the infrastructure device to the target infrastructure device. The LTM handover process consists only of signaling at the physical layer and / or the media access control (MAC) layer at each of the infrastructure equipment, target infrastructure equipment, and communication devices.

[0146] Paragraph 41. A wireless communication system comprising a communication device according to paragraph 19 and a source infrastructure device according to paragraph 39.

[0147] Paragraph 42. A computer program comprising instructions that, when loaded onto a computer, cause the computer to perform a method according to any one of paragraphs 1 to 18 or paragraphs 21 to 38.

[0148] Paragraph 43. A non-transitory computer-readable storage medium storing a computer program according to paragraph 42.

[0149] It is understood that the above description, for clarity, refers to different functional units, circuits, and / or processors. However, it is obvious that any appropriate functional allocation among the different functional units, circuits, and / or processors can be used without departing from the implementation.

[0150] The described embodiments can be implemented in any suitable form, including hardware, software, firmware, or any combination thereof. The described embodiments can optionally be implemented, at least in part, as computer software running on one or more data processors and / or digital signal processors. Elements and components of any embodiment can be implemented physically, functionally, and logically in any suitable manner. In practice, functionality can be implemented in a single unit, in multiple units, or as part of other functional units. Therefore, the disclosed embodiments can be implemented in a single unit or can be physically and functionally distributed among different units, circuits, and / or processors.

[0151] Although this disclosure has been described in conjunction with some embodiments, it is not intended to be limited to the specific forms set forth herein. Furthermore, while features may appear to be described in conjunction with particular embodiments, those skilled in the art will recognize that the various features of the described embodiments can be combined in any suitable manner to implement the technology.

[0152] References

[0153] [1] Holma H. ​​and Toskala A, "LTE for UMTS OFDMA and SC-FDMA basedradio access", John Wiley and Sons, 2009.

[0154] [2] TS 38.470, "3rd Generation Partnership Project; TechnicalSpecification Group Radio Access Network; NG-RAN; F1 general aspects andprinciples (Release 17)", 3GPP, V17.4.0, March 2023.

[0155] [3] TS 38.473, "3rd Generation Partnership Project; TechnicalSpecification Group Radio Access Network; NG-RAN; F1 application protocol(F1AP) (Release 17)", 3GPP, V17.4.1, April 2023.

[0156] [4] TS 38.401, "3rd Generation Partnership Project; TechnicalSpecification Group Radio Access Network; NG-RAN; Architecture description (Release 17)", 3GPP, V17.4.0, March 2023.

[0157] [5] TS 38.472, "3rd Generation Partnership Project; TechnicalSpecification Group Radio Access Network; NG-RAN; F1 signalling transport(Release 15)", 3GPP, V15.2.0, September 2018.

[0158] [6] TS 38.300, "3rd Generation Partnership Project; TechnicalSpecification Group Radio Access Network; NR; NR and NG-RAN OverallDescription; Stage 2 (Release 17)", 3GPP, V18.0.0, January 2024.

[0159] [7] TS 23.501, "3rd Generation Partnership Project; TechnicalSpecification Group Services and System Aspects; System architecture for the5G System (5GS); Stage 2 (Release 18)", 3GPP, V18.2.0, June 2023.

[0160] [8] TS 36.300, "3rd Generation Partnership Project; TechnicalSpecification Group Radio Access Network; Evolved Universal Terrestrial RadioAccess (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN); Overall description; Stage 2 (Release 17)", 3GPP, V17.4.0, March2023.

[0161] [9] RP-234036, "New WID: NR mobility enhancements Phase 4", Intel,3GPP TSG RAN Meeting #102, December 2023.

Claims

1. A method of operating a communication device, the method comprising: The communication device receives one or more conditional lower-layer triggered mobility LTM handover commands from a source infrastructure device to which it is connected. Each conditional LTM handover command includes an indication of at least one target infrastructure device and an indication of one or more conditions. If the one or more conditions are met, the communication device will perform an LTM handover procedure to switch from the source infrastructure device to the target infrastructure device. The LTM handover process consists only of signaling at the physical layer and / or the Media Access Control (MAC) layer at each of the source infrastructure device, the target infrastructure device, and the communication device.

2. The method according to claim 1, comprising: Determine that one or more conditions indicated by one of the received conditional LTM handover commands are met, and The LTM handover process is performed to switch from the source infrastructure device to the target infrastructure device, as indicated by the received conditional LTM handover command, where the communication device determines that one or more conditions are met.

3. The method according to claim 1, wherein, The one or more conditions include that the quality of the physical layer signal received from the target infrastructure device is at least a predetermined amount higher than the quality of the physical layer signal received from the source infrastructure device.

4. The method according to claim 1, wherein, One or more of the conditions include that the quality of the physical layer signal received from the target infrastructure device is higher than a predetermined threshold.

5. The method according to claim 1, wherein, The one or more conditions include the quality of the physical layer signal received from the source infrastructure device being lower than a predetermined threshold and the quality of the physical layer signal received from the target infrastructure device being higher than the predetermined threshold.

6. The method according to claim 1, comprising: Receive MAC control element CE from the source infrastructure device, wherein the MAC CE includes all of one or more conditional LTM switching commands.

7. The method according to claim 1, comprising: Receive one or more MAC CEs from the source infrastructure device, wherein each MAC CE includes one of one or more conditional LTM handover commands.

8. The method according to claim 1, comprising: Before receiving one or more conditional LTM handover commands, a measurement report is sent to the source infrastructure device. The measurement report includes indications of measurements performed by the communication device on physical layer signals received from one or more candidate infrastructure devices, which are candidates for at least one target infrastructure device indicated in each of the one or more conditional LTM handover commands. After sending the measurement report and before receiving the one or more conditional LTM handover commands, the allocation of radio resources for each of the at least one target infrastructure device indicated by each of the one or more conditional LTM handover commands is received from the source infrastructure device.

9. The method according to claim 1, comprising: Before receiving one or more conditional LTM handover commands, a Radio Resource Control (RRC) configuration message is received from the source infrastructure device. The RRC configuration message includes the allocation of radio resources for each of one or more candidate infrastructure devices, which are candidates for at least one target infrastructure device indicated in each of the one or more conditional LTM handover commands. After receiving the RRC configuration message and before receiving the one or more conditional LTM handover commands, a measurement report is sent to the source infrastructure device. The measurement report includes an indication of measurements performed by the communication device on physical layer signals received from the one or more candidate infrastructure devices. After sending the measurement report and before receiving the one or more conditional LTM handover commands, an indication is received from the source infrastructure device indicating that radio resources allocated by the RRC configuration message to candidate infrastructure devices not in at least one of the target infrastructure devices indicated in each of the one or more conditional LTM handover commands are released.

10. The method according to claim 1, comprising: Before receiving one or more conditional LTM handover commands, an RRC configuration message is received from the source infrastructure device. The RRC configuration message includes the allocation of radio resources for each of one or more candidate infrastructure devices, which are candidates for at least one target infrastructure device indicated in each of the one or more conditional LTM handover commands. It is determined that the radio resources allocated by the RRC configuration message will be released after a predetermined time period.

11. The method according to claim 10, wherein, The predetermined time period begins when the communication device receives at least one conditional LTM handover command.

12. The method according to claim 10, wherein, The predetermined time period begins when the communication device receives a physical layer signaling message from the source infrastructure device.

13. The method according to claim 10, wherein, The predetermined time period is indicated in at least one conditional LTM switching command.

14. The method of claim 10, comprising: Receive an RRC message from the source infrastructure device, including an indication of the predetermined time period.

15. The method according to claim 1, comprising: Before receiving one or more conditional LTM handover commands, an RRC configuration message is received from the source infrastructure device. The RRC configuration message includes the allocation of radio resources for each of one or more candidate infrastructure devices, which are candidates for at least one target infrastructure device indicated in each of the one or more conditional LTM handover commands, wherein the allocated radio resources are deactivated. After receiving the RRC configuration message and before receiving the one or more conditional LTM handover commands, a measurement report is sent to the source infrastructure device. The measurement report includes an indication of measurements performed by the communication device on physical layer signals received from the one or more candidate infrastructure devices. After sending the measurement report and before receiving the one or more conditional LTM handover commands, an indication is received from the source infrastructure device indicating that the radio resources allocated by the RRC configuration message for the candidate infrastructure device in each of the at least one target infrastructure device indicated in the one or more conditional LTM handover commands are activated.

16. The method of claim 1, comprising: Before receiving one or more conditional LTM handover commands, an RRC configuration message is received from the source infrastructure device. The RRC configuration message includes the allocation of radio resources for each of one or more candidate infrastructure devices, which are candidates for at least one target infrastructure device indicated in each of the one or more conditional LTM handover commands, wherein the allocated radio resources are deactivated. After receiving the RRC configuration message and before receiving the one or more conditional LTM handover commands, a measurement report is sent to the source infrastructure device. The measurement report includes an indication of measurements performed by the communication device on physical layer signals received from the one or more candidate infrastructure devices. Each of the one or more conditional LTM handover commands includes an indication that the radio resources allocated by the RRC configuration message for the candidate infrastructure device in the at least one target infrastructure device indicated by the conditional LTM handover command are activated.

17. The method according to claim 1, comprising: Before receiving one or more conditional LTM handover commands, an RRC configuration message is received from the source infrastructure device. The RRC configuration message includes indications for one or more candidate infrastructure devices, which are candidates for at least one target infrastructure device indicated in each of the one or more conditional LTM handover commands. The maximum number of target infrastructure devices indicated by the one or more conditional LTM handover commands is less than the maximum number of candidate infrastructure devices indicated by the RRC configuration message.

18. The method of claim 1, comprising: Before receiving one or more conditional LTM handover commands, a measurement report is sent to the source infrastructure device. The measurement report includes indications of measurements performed by the communication device on physical layer signals received from one or more candidate infrastructure devices, which are candidates for at least one target infrastructure device indicated in each of the one or more conditional LTM handover commands. Based on commands received from the source infrastructure device after sending the measurement report, synchronization is performed with one or more of the candidate infrastructure devices in the downlink and / or uplink.

19. A communication device, comprising: Transceiver circuitry, configured to transmit and / or receive signals, and A controller circuit is configured to combine with the transceiver circuitry to receive one or more conditional lower-layer triggered mobility LTM handover commands from a source infrastructure device to which the communication device is connected. Each conditional LTM handover command includes an indication of at least one target infrastructure device and an indication of one or more conditions. If the one or more conditions are met, the communication device will perform an LTM handover procedure to switch from the source infrastructure device to the target infrastructure device. The LTM handover process consists only of signaling at the physical layer and / or the Media Access Control (MAC) layer at each of the source infrastructure device, the target infrastructure device, and the communication device.

20. A circuit for a communication device, the circuit comprising: Transceiver circuitry, configured to transmit and / or receive signals, and A controller circuit is configured to combine with the transceiver circuitry to receive one or more conditional lower-layer triggered mobility LTM handover commands from a source infrastructure device to which the communication device is connected. Each conditional LTM handover command includes an indication of at least one target infrastructure device and an indication of one or more conditions. If the one or more conditions are met, the communication device will perform an LTM handover procedure to switch from the source infrastructure device to the target infrastructure device. The LTM handover process consists only of signaling at the physical layer and / or the Media Access Control (MAC) layer at each of the source infrastructure device, the target infrastructure device, and the communication device.

21. A method of operating infrastructure equipment of a wireless communication network, said infrastructure equipment being a source infrastructure equipment to which a communication device is connected, the method comprising: One or more conditional low-layer triggered mobility LTM handover commands are sent to the communication device, wherein each conditional LTM handover command includes an indication of at least one target infrastructure device and an indication of one or more conditions. If the one or more conditions are met, the communication device will perform an LTM handover procedure to switch from the infrastructure device to the target infrastructure device. The LTM handover process consists only of signaling at the physical layer and / or the Media Access Control (MAC) layer at each of the infrastructure device, the target infrastructure device, and the communication device.

22. The method according to claim 21, wherein, The one or more conditions include that the quality of the physical layer signal received at the communication device from the target infrastructure device is higher than the quality of the physical layer signal sent from the infrastructure device to the communication device by at least a predetermined amount.

23. The method according to claim 21, wherein, One or more of the conditions include the quality of the physical layer signal received at the communication device from the target infrastructure device being higher than a predetermined threshold.

24. The method according to claim 21, wherein, The one or more conditions include a physical layer signal quality that is lower than a predetermined threshold transmitted from the infrastructure equipment to the communication device and a physical layer signal quality that is higher than the predetermined threshold received at the communication device from the target infrastructure equipment.

25. The method of claim 21, comprising: The communication device is sent a Media Access Control (MAC) control element (CE), wherein the MAC CE includes all of one or more conditional LTM switching commands.

26. The method of claim 21, comprising: Send one or more MAC CEs to the communication device, wherein each MAC CE includes one of one or more conditional LTM switching commands.

27. The method of claim 21, comprising: Before sending one or more conditional LTM handover commands, a measurement report is received from the communication device. The measurement report includes indications from the communication device of measurements performed on physical layer signals received from one or more candidate infrastructure devices, which are candidates for at least one target infrastructure device indicated in each of the one or more conditional LTM handover commands. After receiving the measurement report and before sending the one or more conditional LTM handover commands, the communication device is sent with the allocation of radio resources for each of the at least one target infrastructure device indicated in each of the one or more conditional LTM handover commands.

28. The method of claim 21, comprising: Before sending one or more conditional LTM handover commands, a Radio Resource Control (RRC) configuration message is sent to the communication device. The RRC configuration message includes the allocation of radio resources for each of one or more candidate infrastructure devices, which are candidates for at least one target infrastructure device indicated in each of the one or more conditional LTM handover commands. After sending the RRC configuration message and before sending the one or more conditional LTM handover commands, a measurement report is received from the communication device. The measurement report includes an indication of measurements performed by the communication device on physical layer signals received from the one or more candidate infrastructure devices. After receiving the measurement report and before sending the one or more conditional LTM handover commands, an indication is sent to the communication device indicating that radio resources allocated by the RRC configuration message for candidate infrastructure devices not in each of the at least one target infrastructure device indicated in the one or more conditional LTM handover commands are released.

29. The method of claim 21, comprising: Before sending one or more conditional LTM handover commands, a Radio Resource Control (RRC) configuration message is sent to the communication device. The RRC configuration message includes the allocation of radio resources for each of one or more candidate infrastructure devices, which are candidates for at least one target infrastructure device indicated in each of the one or more conditional LTM handover commands. After sending the RRC configuration message and before sending the one or more conditional LTM handover commands, a measurement report is received from the communication device. The measurement report includes an indication of measurements performed by the communication device on physical layer signals received from the one or more candidate infrastructure devices. After receiving the measurement report and before sending the one or more conditional LTM handover commands, an indication is sent to a candidate infrastructure device that is not among the at least one target infrastructure device indicated in each of the one or more conditional LTM handover commands, the indication indicating that the radio resources allocated by the RRC configuration message for the candidate infrastructure device that is not among the at least one target infrastructure device indicated in each of the one or more conditional LTM handover commands are released.

30. The method of claim 21, comprising: Before sending one or more conditional LTM handover commands, an RRC configuration message is sent to the communication device. The RRC configuration message includes the allocation of radio resources for each of one or more candidate infrastructure devices, which are candidates for the at least one target infrastructure device indicated in each of the one or more conditional LTM handover commands. The radio resources allocated by the RRC configuration message will be released after a predetermined time period.

31. The method according to claim 30, wherein, The predetermined time period begins when the communication device receives at least one conditional LTM handover command.

32. The method according to claim 30, wherein, The predetermined time period begins when the communication device receives a physical layer signaling message from the infrastructure device.

33. The method according to claim 30, wherein, The predetermined time period is indicated in at least one conditional LTM switching command.

34. The method of claim 30, comprising: Send an RRC message, including an indication of the predetermined time period, to the communication device.

35. The method of claim 21, comprising: Before sending one or more conditional LTM handover commands, an RRC configuration message is sent to the communication device. The RRC configuration message includes the allocation of radio resources for each of one or more candidate infrastructure devices, which are candidates for the at least one target infrastructure device indicated in each of the one or more conditional LTM handover commands, wherein the allocated radio resources are deactivated. After sending the RRC configuration message and before sending the one or more conditional LTM handover commands, a measurement report is received from the communication device. The measurement report includes an indication of measurements performed by the communication device on physical layer signals received from the one or more candidate infrastructure devices. After receiving the measurement report and before sending the one or more conditional LTM handover commands, an indication is sent to the communication device indicating that the radio resources allocated by the RRC configuration message for the candidate infrastructure device in each of the at least one target infrastructure device indicated in the one or more conditional LTM handover commands are activated.

36. The method of claim 21, comprising: Before sending one or more conditional LTM handover commands, an RRC configuration message is sent to the communication device. The RRC configuration message includes radio resource allocation for each of one or more candidate infrastructure devices, which are candidates for at least one target infrastructure device indicated in each of the one or more conditional LTM handover commands, wherein the allocated radio resources are deactivated. After sending the RRC configuration message and before sending the one or more conditional LTM handover commands, a measurement report is received from the communication device, the measurement report including an indication of measurements performed by the communication device on physical layer signals received from the one or more candidate infrastructure devices. Each of the one or more conditional LTM handover commands includes an indication that the radio resources allocated by the RRC configuration message for the candidate infrastructure device in the at least one target infrastructure device indicated by the conditional LTM handover command are activated.

37. The method of claim 21, comprising: Before sending one or more conditional LTM handover commands, an RRC configuration message is sent to the communication device. The RRC configuration message includes indications of one or more candidate infrastructure devices, which are candidates for at least one target infrastructure device indicated in each of the one or more conditional LTM handover commands. The maximum number of target infrastructure devices indicated by the one or more conditional LTM handover commands is less than the maximum number of candidate infrastructure devices indicated by the RRC configuration message.

38. The method of claim 21, comprising: Before sending one or more conditional LTM handover commands, a measurement report is received from the communication device. The measurement report includes indications from the communication device of measurements performed on physical layer signals received from one or more candidate infrastructure devices, which are candidates for at least one target infrastructure device indicated in each of the one or more conditional LTM handover commands. After receiving the measurement report, a command is sent to the communication device to perform synchronization with one or more candidate infrastructure devices in the downlink and / or uplink.

39. An infrastructure device for a wireless communication network, said infrastructure device being a source infrastructure device to which a communication device is connected, said infrastructure device comprising: Transceiver circuitry, configured to transmit and / or receive signals, and A controller circuit is configured to combine with the transceiver circuitry to send one or more conditional low-level triggered mobility LTM handover commands to the communication device, wherein each conditional LTM handover command includes an indication of at least one target infrastructure device and an indication of one or more conditions, if the one or more conditions are met, the communication device will perform an LTM handover procedure to hand over from the infrastructure device to the target infrastructure device. The LTM handover process consists only of signaling at the physical layer and / or the Media Access Control (MAC) layer at each of the infrastructure device, the target infrastructure device, and the communication device.

40. A circuit for an infrastructure device in a wireless communication network, the infrastructure device being a source infrastructure device to which a communication device is connected, the circuit comprising: Transceiver circuitry, configured to transmit and / or receive signals, and A controller circuit is configured to combine with the transceiver circuitry to send one or more conditional low-level triggered mobility LTM handover commands to the communication device, wherein each conditional LTM handover command includes an indication of at least one target infrastructure device and an indication of one or more conditions, if the one or more conditions are met, the communication device will perform an LTM handover procedure to hand over from the infrastructure device to the target infrastructure device. The LTM handover process consists only of signaling at the physical layer and / or the Media Access Control (MAC) layer at each of the infrastructure device, the target infrastructure device, and the communication device.

41. A wireless communication system comprising the communication device according to claim 19 and the source infrastructure equipment according to claim 39.

42. A computer program comprising instructions that, when loaded onto a computer, cause the computer to perform the method according to claim 1 or claim 21.

43. A non-transitory computer-readable storage medium storing a computer program according to claim 42.

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