Communication device, infrastructure equipment and method

Abstract

A method of operating a source infrastructure device of a wireless communication network in conditional switching is provided. The method includes configuring one or more conditions that trigger a handover of the communication device from a source cell provided by a source infrastructure equipment to a target cell provided by a target infrastructure equipment of the wireless communication network. The method includes transmitting to the communication device an indication of one or more conditions that trigger a handover of the communication device from a source cell to a target cell. The method includes determining that a network energy saving (NES) mode of at least one of a source cell and a target cell has changed or is expected to change. In response, the method includes transmitting an evaluation trigger signal to the communication device. The evaluation trigger signal indicates to the communication device an evaluation of one or more of conditions to trigger a handover of the communication device from a source cell to a target cell.

Description

background Technical Field

[0001] The present disclosure relates to a communication device, infrastructure equipment of a wireless communication network, and a method of operating the communication device and the infrastructure equipment of the wireless communication network in conditional handover.

[0002] This application claims the Paris Convention priority of European Patent Application No. EP22216609.2, the content of which is incorporated herein by reference in its entirety. Background Art

[0003] The "background" description provided herein is for the purpose of generally presenting the context of the present disclosure. The work of the presently named inventors is neither explicitly nor implicitly admitted to be prior art with respect to the present invention to the extent described in this background section and insofar as it may not have been described as prior art at the time of filing.

[0004] Third and fourth generation mobile telecommunication systems (such as those based on the UMTS and Long Term Evolution (LTE) architectures defined by 3GPP) are capable of supporting more complex services than the simple voice and messaging services provided by previous generations of mobile telecommunication systems. For example, utilizing the improved wireless interface and enhanced data rates provided by LTE systems, users are able to enjoy high data rate applications, such as mobile video streaming and mobile video conferencing, which were previously only available via fixed-line data connections. Consequently, there is a strong demand for the deployment of such networks, and the coverage areas of these networks (i.e., the geographic locations where access to the network is possible) are expected to increase more rapidly.

[0005] Future wireless communication networks will be expected to routinely and efficiently support communications with a wider range of devices associated with a wider range of data traffic characteristics and types than current systems are optimized to support. For example, future wireless communication networks are expected to efficiently support communications with devices including reduced complexity devices, machine type communication (MTC) devices, high-resolution video displays, virtual reality headsets, and the like. 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," and may typically be associated with the transmission of relatively small amounts of data with relatively high latency tolerance.

[0006] In view of this, it is expected that future wireless communication networks (such as those that may be referred to as 5G or New Radio (NR) systems / New Radio Access Technology (RAT) systems [1]) as well as future iterations / versions of existing systems will need to efficiently support connectivity for a wide range of devices associated with different applications and with different characterized data traffic characteristics. Connectivity of these devices is conventionally maintained by using a so-called "handover" process, in which a communication device changes its access point to the wireless communication network in response to an instruction from the wireless communication network or in response to one or more conditions being met. In view of the wide range of device types and capabilities in future wireless communication networks, there is a need for improved handover processes. Summary of the Invention

[0007] The present disclosure may help to solve or alleviate at least some of the problems discussed above.

[0008] Example embodiments may provide a method for operating source infrastructure equipment of a wireless communication network in conditional handover. The method includes configuring one or more conditions that trigger a communication device to switch from a source cell provided by the source infrastructure equipment to a target cell provided by a target infrastructure equipment of the wireless communication network. The method includes transmitting, to the communication device, an indication of the one or more conditions that trigger the communication device to switch from the source cell to the target cell. The method includes determining that a network energy saving (NES) mode of at least one of the source cell and the target cell has changed or is expected to change. In response, the method includes transmitting an evaluation trigger signal to the communication device. The evaluation trigger signal instructs the communication device to evaluate one or more of the conditions that trigger the communication device to switch from the source cell to the target cell.

[0009] Exemplary embodiments may also provide a method for operating a communication device in conditional handover. The method includes receiving an indication of one or more conditions that trigger the communication device to switch from a source cell provided by the source infrastructure device to a target cell provided by a target infrastructure of the wireless communication network from a source infrastructure device of a wireless communication network. The method includes receiving an evaluation trigger signal from the source infrastructure device, the evaluation trigger signal instructing the communication device to evaluate one or more of the conditions that trigger the communication device to switch from the source cell to the target cell. In response to a change or an expected change in a network energy saving NES mode of at least one of the source cell and the target cell, the communication device receives the evaluation trigger signal from the source infrastructure device. In response, the method includes evaluating one or more of the conditions that trigger the communication device to switch from the source cell to the target cell. The method includes determining that one or more of the evaluated conditions have been met. In response, the method includes initiating handover of the communication device from the source cell to the target cell.

[0010] Embodiments may provide energy-efficient conditional handover in a wireless communication network by transmitting an evaluation trigger signal to a communication device in response to determining that the NES mode of at least one of a source cell and a target cell has changed or is expected to change. Transmission of the evaluation trigger signal allows the wireless communication network to control when the communication device evaluates one or more handover conditions based on the change or expected change in the NES mode of at least one of the source cell and the target cell. Because the communication device evaluates one or more of the conditions in response to receiving the evaluation trigger signal (rather than the periodic or continuous evaluation characteristic of conventional conditional handover), fewer condition evaluations are expected before reaching a positive evaluation result (i.e., determining that one or more of the conditions are satisfied), thereby reducing energy consumption in the wireless communication network. Furthermore, as will be understood from the detailed description below, transmitting the evaluation trigger signal in response to determining that the NES mode of at least one of the source cell and the target cell has changed or is expected to change means that the communication device can switch cells (or remain in a cell) in response to the change or expected change in the NES mode. For example, the wireless communication network can efficiently control which communication devices are in which cells in response to changes in the NES mode according to, for example, a network planning policy.

[0011] Accordingly, aspects and features of the disclosure are defined in the appended claims.

[0012] It should be understood that the foregoing general description and the following detailed description are exemplary of the present technology and not restrictive of the present technology. The described embodiments and further advantages will be best understood by reference to the following detailed description taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] A more complete appreciation of the present disclosure and many of its attendant advantages will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings, in which like reference numerals designate identical or corresponding components throughout the several views, and:

[0014] Figure 1 schematically represents some aspects of an LTE-type wireless telecommunications system that may be configured to operate in accordance with certain embodiments of the present disclosure;

[0015] Figure 2 schematically illustrates some aspects of a new radio access technology (RAT) wireless telecommunications system that may be configured to operate in accordance with certain embodiments of the present disclosure;

[0016] Figure 3 is a schematic block diagram of an example of a source infrastructure device controlling a handover of a communication apparatus to a target infrastructure device;

[0017] Figure 4Schematically represents the conventional condition switching process;

[0018] Figure 5 is a flow chart illustrating a method of operating a source infrastructure device of a wireless communication network in a conditional handover according to an exemplary embodiment;

[0019] Figure 6 is a flowchart illustrating a method of operating a communication device in conditional handover according to an exemplary embodiment. DETAILED DESCRIPTION

[0020] Long Term Evolution (4G)

[0021] Figure 1 A schematic diagram is provided illustrating certain basic functionality of a mobile telecommunication network / system 100 that typically operates according to LTE principles, but which may also support other radio access technologies, and which may be suitable for implementing embodiments of the present disclosure as described herein. Figure 1 Specific aspects of the various elements and their corresponding modes of operation are well known and defined in the relevant standards managed by the 3GPP (RTM) body and are also described in a number of books on the subject (e.g., Holma H. and Toskala A [2]). It should be understood that operational aspects of the telecommunications network discussed herein that are not specifically described (e.g., with respect to specific communication protocols and physical channels used for communication between the different elements) may be implemented in accordance with any known technology (e.g., in accordance with the relevant standards and known proposed modifications and additions to the relevant standards).

[0022] Network 100 includes multiple base stations 101 connected to a core network unit 102. Each base station provides a coverage area 103 (e.g., a cell) within which data can be transmitted to and from communication devices 104. Data is transmitted from a base station 101 to a communication device 104 within its respective coverage area 103 via a wireless downlink. Data is transmitted from a communication device 104 to a base station 101 via a wireless uplink. Core network unit 102 routes data to and from the communication device 104 via the respective base station 101 and provides functions such as authentication, mobility management, and billing. A communication device may also be referred to as a mobile station, user equipment (UE), user terminal, mobile wireless device, terminal device, etc. A base station, as an example of network infrastructure equipment / network access node, may also be referred to as a transceiver station / nodeB / e-nodeB, g-nodeB (gNB), etc. In this regard, different terms are often associated with different generations of wireless telecommunication systems, used to describe elements that provide substantially equivalent functionality. However, exemplary embodiments of the present disclosure can be implemented equally across different generations of wireless telecommunication systems (such as 5G or New Wireless, as explained below), and for simplicity, specific terms may be used regardless of the underlying network architecture. That is, the use of specific terms with respect to specific exemplary implementations is not intended to limit these implementations to the specific generation of networks that may be most closely associated with the specific terms.

[0023] New wireless access technology (5G)

[0024] Figure 2 is a schematic diagram illustrating the network architecture of a new RAT wireless communication network / system 200 based on previously proposed methods, which may also be adapted to provide functionality according to embodiments of the present disclosure as described herein. Figure 2The new RAT network 200 shown in FIG. 1 includes a first communication cell 201 and a second communication cell 202. Each communication cell 201, 202 includes a control node (centralized unit) 221, 222 that communicates with a core network component 210 via corresponding wired or wireless links 251, 252. The corresponding control nodes 221, 222 also each communicate with a plurality of distributed units (radio access nodes / remote transmission and reception points (TRPs)) 211, 212 in their corresponding cells. Again, these communications can be carried out via corresponding wired or wireless links. The distributed units 211, 212 are responsible for providing a wireless access interface for communication devices connected to the network. Each distributed unit 211, 212 has a coverage area (wireless access coverage range) 241, 242, wherein the sum of the coverage areas of the distributed units under the control of the control node together defines the coverage range of the corresponding communication cell 201, 202. Each distributed unit 211 , 212 includes transceiver circuitry for transmitting and receiving wireless signals and processor circuitry configured to control the respective distributed unit 211 , 212 .

[0025] In terms of broad top-level functionality, Figure 2 The core network component 210 of the new RAT communication network represented in FIG can be broadly considered to be similar to Figure 1 The core network 102 shown in FIG. 1 corresponds to the core network 102, and the corresponding control nodes 221, 222 and their associated distributed units / TRPs 211, 212 can be broadly considered to provide Figure 1 The term network infrastructure equipment / access node may be used to encompass these elements as well as more conventional base station-type elements of wireless communication systems. Depending on the intended application, the responsibility for scheduling transmissions scheduled over the wireless interface between the corresponding distributed units and the communication devices may lie with the control node / centralized unit and / or the distributed units / TRP.

[0026] The communication device or UE 260 is Figure 2 201. Thus, the communication device 260 may exchange signaling with the first control node 221 in the first communication cell via one of the distributed units 211 associated with the first communication cell 201. In some cases, communications for a given communication device may be routed through only one of the distributed units, but it should be understood that in some other implementations, communications associated with a given communication device may be routed through more than one distributed unit (e.g., in soft handover scenarios and other scenarios).

[0027] exist Figure 2In the example, for simplicity, two communication cells 201, 202 and one communication device 260 are shown, but it should of course be understood that in practice, the system may include a larger number of communication cells (each supported by a corresponding control node and multiple distributed units) serving a larger number of communication devices.

[0028] It should be further understood that Figure 2 Only one example of the architecture of the proposed new RAT communication system is presented, in which the method according to the principles described herein may be employed, and in terms of wireless communication systems having different architectures the functionalities disclosed herein may also be applied.

[0029] Thus, exemplary embodiments of the present disclosure as discussed herein may be implemented according to various architectures such as Figure 1 and Figure 2 The exemplary architecture shown in FIG. 1 is implemented in a wireless telecommunications system / network. It should therefore be understood that the specific wireless communication architecture in any given implementation is not particularly important to the principles described herein. In this regard, exemplary embodiments of the present disclosure may generally be described in the context of communications between network infrastructure equipment / access nodes and communication devices, where the specific nature of the network infrastructure equipment / access nodes and communication devices will depend on the network infrastructure for the implementation to be used. For example, in some scenarios, the network infrastructure equipment / access nodes may include base stations (such as Figure 1 LTE-type base station 101 as shown, which is suitable for providing functionality according to the principles described herein, and in other examples, network infrastructure equipment / access points may include Figure 2 Control units / control nodes 221 , 222 and / or TRPs 211 , 212 of the kind shown are adapted to provide functionality according to the principles described herein.

[0030] Figure 3 A detailed description of the wireless communication network in which the handover can be performed is shown in FIG. Figure 3 As will be appreciated, the communication device 502 switches from a source cell provided by the source infrastructure equipment 504 to a target cell provided by the target infrastructure equipment 506. For clarity, the source cell and the target cell are not shown in FIG. Figure 3 However, it should be understood that the source cell and the target cell may be roughly the same as those described above. Figure 1 and Figure 2 The cells 3 and 12 in question correspond. The source infrastructure equipment 504 and the target infrastructure equipment 506 form part of a radio access network to a core network 508. It will be appreciated that the communication device 502 is a communication device such as Figure 2 In one example, the communication device 502 may be a UE.

[0031] Prior to the handover, the communications apparatus 502 transmits signals on the uplink (UL) and receives signals on the downlink (DL) from the source infrastructure device 504. The source infrastructure device 504 and the target infrastructure device 506 can each be considered to be a combination of the gNB 101 or the control node 221 and the TRP 211. Prior to the handover, the communications apparatus 502 is shown transmitting uplink data to the source infrastructure device 504 via the uplink resources (UL) of the wireless access interface, as generally illustrated by the dashed arrow 274b directed toward the source infrastructure device 504. The communications apparatus 502 can similarly be configured to receive downlink data transmitted by the source infrastructure device 504 via the downlink resources (DL), as indicated by the dashed arrow 288b from the source infrastructure device 504 to the communications apparatus 502. After the handover, the communications apparatus 502 is shown transmitting uplink data to the target infrastructure device 506 via the uplink resources (UL) of the wireless access interface, as generally illustrated by the solid arrow 288a directed toward the target infrastructure device 506. The communication apparatus 502 may similarly be configured to receive downlink data transmitted by the target infrastructure equipment 506 via the downlink resources DL, as indicated by the solid arrow 274a from the target infrastructure equipment 506 to the communication apparatus 502 .

[0032] exist Figure 3 , the source infrastructure device 504 and the target infrastructure device 506 are each connected to the core network 508 via interfaces 278, 279 to controllers 504c, 506c of the respective infrastructure devices 504. The source infrastructure device 504 and the target infrastructure device 506 each include a receiver 504b, 506b connected to antennas 504d, 506d, and a transmitter 504a, 506a connected to antennas 504d, 506d. Correspondingly, the communication apparatus 502 includes a controller 502c connected to a receiver 502b that receives a signal from an antenna 502d, and a transmitter 502a also connected to antenna 502d.

[0033] The controllers 504c, 506c are configured to control the source infrastructure equipment 504 and the target infrastructure equipment 506, respectively, and may include processor circuitry that may in turn include various subunits / subcircuits for providing functionality as further explained herein. These subunits may be implemented as discrete hardware elements or as appropriately configured functions of the processor circuitry. Thus, the controllers 504c, 506c may include circuitry that is appropriately configured / programmed to provide the desired functionality using conventional programming / configuration techniques for equipment in wireless telecommunications systems. The transmitters 504a, 506a and receivers 504b, 506b may include signal processing and radio frequency filters, amplifiers, and circuitry according to conventional arrangements. For ease of presentation, the transmitters 504a, 506a, receivers 504b, 506b, and controllers 504c, 506c are shown in FIG. Figure 3 Schematically shown as separate elements in FIG. However, it should be understood that the functionality of these elements 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 / circuitry / chips / chip sets. As should be understood, infrastructure equipment 504 will typically include various other elements associated with its operational functionality.

[0034] Correspondingly, the controller 502c of the communication device 502 is configured to control the transmitter 502a and the receiver 502b and may include a processor circuit system, which in turn may include various sub-units / sub-circuits for providing the functionality as further explained herein. These sub-units may be implemented as discrete hardware elements or as functions of a suitable configuration of the processor circuit system. Thus, the controller 502c may include circuit systems that are appropriately configured / programmed to provide the desired functionality using conventional programming / configuration techniques for equipment in wireless telecommunications systems. Similarly, the transmitter 502a and the receiver 502b may include signal processing and radio frequency filters, amplifiers, and circuit systems according to conventional arrangements. For ease of presentation, the transmitter 502a, the receiver 502b, and the controller 502c are shown in FIG. Figure 3 Schematically shown as separate elements. However, it will be appreciated that the functionality of these elements may 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 / circuitry / chips / chip sets. It will be appreciated that the communication device 502 will typically include various other elements associated with its operational functionality, such as a power supply, a user interface, etc., but for simplicity these are not shown. Figure 3 Shown in.

[0035] The controllers 504c, 502c may be configured to execute instructions stored on a computer-readable medium, such as non-volatile memory. The process steps described herein may be performed by, for example, a microprocessor in conjunction with random access memory operating according to instructions stored on a computer-readable medium.

[0036] Conventional conditional switching

[0037] Aspects of NR involve enhanced mobility, and in particular, increased mobility robustness for new services that require low latency and high reliability performance, such as URLLC. Situations may arise where the cell currently serving the UE is no longer suitable, or where the radio link performance between the UE and the source gNB providing coverage within the cell degrades. In such situations, it is often desirable for the UE to be handed over to a cell served by a target gNB. One way to configure a UE to hand over from a source gNB to a target gNB is called "conditional handover."

[0038] Figure 4 An example of conditional switching is illustrated in [3], which is incorporated herein by reference in its entirety. Figure 4 Schematically represents the communication in a wireless communication network between a communication device 502, a source infrastructure device 504, a target infrastructure device 506, other potential target infrastructure devices 511, an access mobility and mobility management function (AMF) 512 and a user plane function (UPF) 514. Figure 4 In the embodiment of the present invention, source infrastructure device 504, target infrastructure device 506, and other potential target infrastructure devices 511 are depicted as "gNBs," but it should be understood that other infrastructure devices of the wireless communication network (e.g., such as eNBs) may be used. AMF 512 and UPF 514 are functions in the core network of the wireless communication network (such as core network 508).

[0039] like Figure 4As shown, prior to handover, communication device 502 communicates user plane data with 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 to configure communication device 502 for conditional handover. In step 3, source infrastructure device 504 transmits a handover request 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 the other potential target infrastructure devices 511 transmit a handover request confirmation to the source infrastructure device 504. In response to receiving the handover request confirmation, the source infrastructure device 504 transmits a conditional handover configuration message to the communication device 502 in step 6. The conditional handover configuration message can be a radio resource control (RRC) configuration message. The conditional handover configuration message includes one or more conditions that trigger the communication device 502 to switch from the source cell provided by the source infrastructure device 504. For example, the one or more conditions in the conditional handover configuration message may include one or more conditions that must be met to trigger a handover to the target cell provided by the target infrastructure device 506 and one or more other conditions that must be met to trigger a handover to other target cells provided by other potential target infrastructure devices 511. The conditions included in the conditional handover configuration message are explained in more detail below. After receiving the conditional handover configuration message, the communication device 502 transmits an RRC reconfiguration complete message to the source infrastructure device 504. After receiving the conditional handover configuration message, the communication device 502 may continuously or periodically evaluate the conditions for triggering the handover included in the handover configuration message to determine whether the conditions for triggering the handover have been met. When the communication device 502 determines that the conditions for triggering a handover have been met, the communication device 502 initiates a handover. For example, the communication device 502 detaches from the source cell provided by the source infrastructure equipment 504 and attaches to the target cell provided by the target infrastructure equipment 506. Figure 4In the illustrated example, the communication device 502 determines that the conditions triggering a handover to the target infrastructure device 506 are met. While the communication device 502 is evaluating the conditions, the source infrastructure device 604 transmits an early state transition to other potential target infrastructure devices in step 7a, and subsequent user data from the UPF 514 is routed to other potential target infrastructure devices 511 via the source infrastructure device 504. In step 8, the target infrastructure device 506 determines that the communication device 502 has successfully handed over from the source cell provided by the source infrastructure device 504 to the target cell provided by the target infrastructure device 506. In response, in step 8a, the target infrastructure device 506 transmits a handover success message to the source infrastructure device 504. In step 8b, the source infrastructure device 504 transmits an SN state transition message to the target infrastructure device 506. Subsequent user data from the UPF 514 to the source infrastructure device is routed to the target infrastructure device 506. In step 8c, a handover cancel message is transmitted from the source infrastructure device 504 to the target infrastructure device and the other potential target infrastructure devices 511.

[0040] As above Figure 4 As mentioned in step 6, the source infrastructure device 504 may transmit a conditional handover configuration message including one or more conditions for triggering handover to the communication apparatus 502 .

[0041] An example of a condition to be satisfied to trigger a handover of the communication device 502 is "Event A3." If the signal quality of a cell provided by a neighboring infrastructure device (e.g., the target infrastructure device 506 or other potential target infrastructure device 511) becomes higher than the signal quality of the cell provided by the source infrastructure device 504 by a predefined offset, the condition defined by Event A3 is satisfied.

[0042] Another example of a condition to be met to trigger a handover of the communication apparatus 502 is “Event A4.” The condition defined by Event A4 is met if the signal quality of a cell provided by a neighboring infrastructure equipment is greater than an absolute threshold.

[0043] Another example of a condition to be met to trigger a handover of the communication apparatus 502 is "Event A5." The condition defined by Event A5 is met if the signal quality of the cell provided by the source infrastructure equipment 504 is less than an absolute threshold and the signal quality of the neighboring infrastructure equipment is greater than the absolute threshold.

[0044] The "signal quality" mentioned above with respect to the definitions of events A3, A4, and A5 can be measured by the 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 device becomes higher than the measured RSRP of the cell provided by the source infrastructure device 504 by a predefined offset, the communication device 502 can determine that the condition described in event A3 is met. In another example, if the measured RSRP and RSRQ of the cell provided by the neighboring infrastructure device each become higher than the measured RSRP and RSRQ of the cell provided by the source infrastructure device 504 by a predefined offset, it can be determined that the condition described in event A3 is met. In 3GPP organization standard version 16, when determining whether events A3, A4, and / or A5 are met, only one reference signal type and the measurement of at most two signal quality parameters are supported.

[0045] Therefore, each of events A3, A4, and A5 represents a condition for triggering the communication device 502 to switch from the source infrastructure device 504. In order to trigger the switch, it may be sufficient to satisfy only one of the conditions included in the conditional switch configuration message, or the triggering of the switch may require satisfying multiple or all of the conditions in the conditional switch configuration message. In one example, only event A3 is included as a condition, and if event A3 is satisfied, the switch is triggered. In another example, events A3 and A4 are included as conditions, and if event A3 or A4 is satisfied, the switch is triggered. In another example, events A3 and A4 are included as conditions, and if both events A3 and A4 are satisfied, the switch is triggered.

[0046] Further details of events A3, A4 and A5 are provided in TS 36.331, the contents of which are hereby incorporated by reference in their entirety.

[0047] Network Energy Saving (NES)

[0048] In 3PP standard version 18, a new research project on Network Energy Saving (NES) was launched ([4]). The objectives of this research project are as follows:

[0049] (i) Define the base station energy consumption model

[0050] Objective (i) is expected to include adapting the framework of power consumption modeling and evaluation methods for UE power saving in NR (discussed in [5]) to the base station side. This is expected to involve adapting the relative energy consumption of DL and UL (taking into account factors such as power amplifier (PA) efficiency, number of TXRU interfaces, base station loading, etc.), sleep states and associated transition times, and one or more reference parameters / configurations.

[0051] (ii) Define evaluation methods and key performance indicators (KPIs)

[0052] Objective (ii) is expected to include evaluation methods for evaluating system-level network energy consumption and energy savings gains, as well as evaluating / balancing the impact on network and user performance (e.g., spectral efficiency, capacity, user perceived throughput (UPT), latency, handover performance, call drop rate, initial access performance, service level agreement (SLA) guarantees related KPIs), energy efficiency, UE power consumption, and complexity. The evaluation method is expected to focus on reusing existing KPIs where applicable, rather than focusing on a single KPI. In cases where existing KPIs are found to be insufficient, new KPIs may be developed as needed. Which KPIs will be evaluated and how they will be evaluated have not yet been determined.

[0053] (iii) Identify technologies on the gNB and UE side to improve network energy efficiency in both base station transmission and reception

[0054] It is expected that objective (iii) includes leveraging potential support / feedback from the UE and potential UE assistance information to dynamically and / or semi-statically achieve efficient operation and finer granularity adaptation of transmission and / or reception in one or more network energy saving techniques in the time, frequency, space, and power domains. It is also expected that objective (iii) includes information exchange / coordination over the network interface.

[0055] It is expected that this study item will prioritize idle / vacant and low / medium load scenarios, where different loads between the carrier and neighboring cells are allowed. The exact definition of such loads is expected to be determined as part of the study item.

[0056] The following single-carrier and multi-carrier deployment examples are expected to be prioritized in this study item:

[0057] - Urban microcells in FR1, including time division duplex (TDD) massive multiple-input multiple-output (MIMO). This can also model small cells.

[0058] -FR2 beam-based scenario (Note: this scenario can also model small cells)

[0059] - Urban / rural macro cells in FR1, with / without DSS Dynamic Spectrum Sharing (DSS). In the case of DSS, no impact on LTE is expected.

[0060] - Evolved Universal Terrestrial Radio Access New Radio Dual Connectivity (EN-DC) / New Radio Dual Connectivity (NR-DC) macrocell with frequency division duplex (FDD) primary cell (PCell) and TDD / massive MIMO on higher FR1 / FR2 frequencies

[0061] It is intended that existing UEs will be able to continue to access a network implementing Release 18 network energy saving techniques, with the possible exception of techniques developed specifically for greenfield deployments.

[0062] Network Energy Saving (NES) mode

[0063] It has been proposed that cells provided by infrastructure devices of a wireless communication network be configured to operate according to NES modes. Table 1 (extracted from [6]) illustrates an example of the proposed NES modes.

[0064]

[0065] Table 1. Proposed NES modes.

[0066] In Table 1, the transition time T of the NES mode is the time taken for a cell to enter or leave that NES mode. The additional transition energy E of the NES mode is the energy relative to the reference energy required for a cell to enter or leave that NES mode. The relative power P of the NES mode is the power relative to the reference power consumed when a cell enters or leaves that NES mode.

[0067] As will be understood by those skilled in the art, the relative power of the deep sleep NES mode is lower than that of the light sleep NES mode, and the relative power of the light sleep NES mode is lower than that of the micro sleep NES mode. In other words, P1 < P2 < P3. Additionally, as will be understood by those skilled in the art, the relative power of the active UL NES mode has a lower relative power than the active DL NES mode. In other words, P5 < P4.

[0068] Table 2 (extracted from [6]) illustrates examples of the relative power P values of the NES modes shown in Table 1 across different base station classes and reference configuration sets. Additional details regarding the base station classes and reference configuration sets can be found in [6].

[0069]

[0070] Table 2. Relative power of the proposed NES modes.

[0071] In addition to the NES modes proposed in Table 1, other NES modes are also contemplated. For example, a cell can be configured to operate according to an NES mode that has lower relative power than a deep sleep NES mode and requires more transition time. This can be referred to as a dormant sleep or quasi-off NES mode. Another example of an NES mode is an "off" NES mode, in which the cell is turned off and no uplink or downlink data transmission is performed. Those skilled in the art will appreciate that a communication device in a cell in an off NES mode can still receive a reference signal or send a wake-up signal to wake up the cell.

[0072] Configuring network cells to operate according to an NES mode is expected to improve network energy conservation. For example, different cells in a wireless communication network may be configured to operate according to different NES modes based on network planning policies. For example, when uplink / downlink traffic is expected to occur in the cell, a cell may be configured to operate in a micro-sleep NES mode, and when no uplink / downlink traffic is expected in the cell for a considerable period of time, another cell may be configured to operate in a deep-sleep NES mode.

[0073] Enhancements to conditional handover for NES have been discussed in [6] and [7], the contents of which are hereby incorporated by reference in their entirety. Specifically, it has been proposed to enhance conditional handover by making the evaluation of conditional handover conditions dependent on the NES mode of the source / target cell. However, in existing conditional handover processes, the communication device periodically or continuously evaluates the handover conditions, which results in energy waste. In addition, the communication device may not be aware of changes or expected changes in the NES mode of cells in the wireless communication network. Therefore, the communication device may spend too much time in a cell with an NES mode that is not suitable for the communication device, resulting in further energy waste. For example, the communication device may be in a cell that has just turned on the NES mode, but the communication device cannot be unloaded to another cell until it has evaluated the conditions for handover. Therefore, improving the energy efficiency of conditional handover presents a technical challenge.

[0074] Therefore, there is a need for communication apparatus, infrastructure equipment, and methods for improving the energy efficiency of conditional handover in wireless communication networks.

[0075] Figure 5 A method of operating a source infrastructure device of a wireless communication network in a conditional handover according to an exemplary embodiment is shown in FIG. The method starts at step S1 .

[0076] After step S1 , in step S2 , the method comprises configuring one or more conditions that trigger handover of the communication device from a source cell provided by the source infrastructure equipment to a target cell provided by the target infrastructure equipment of the wireless communication network.

[0077] The one or more conditions may be explicitly or implicitly based on the NES mode of at least one of the source cell and the target cell. An example of an explicit condition based on the NES mode of the target cell is that if the target cell is configured to operate according to a light sleep or micro sleep NES mode, the communication device will switch to the target cell. An example of an implicit condition based on the NES mode of the target cell is that if the communication device detects that the reference signal received power (RSRP) of the target cell is higher than a predefined threshold, the communication device will switch to the target cell. In this example, the target cell may be configured to operate according to a deep sleep NES mode, and the source infrastructure device configures the RSRP threshold to be relatively high because the target cell is in a deep sleep NES mode. Similarly, if the target cell is configured to operate according to a light sleep NES mode, the source infrastructure device may configure the RSRP threshold to be relatively low (i.e., lower than when the target cell is configured to operate according to a deep sleep NES mode). Other examples of conditions that trigger a handover are discussed in the section "Exemplary Handover Conditions" below.

[0078] After step S2, in step S3, the method includes transmitting to the communication device an indication of one or more conditions that trigger a handover of the communication device from the source cell to the target cell. For example, the source infrastructure equipment may transmit a conditional handover configuration message (such as Figure 4 For example, the conditional handover message may be transmitted as an RRC signal.

[0079] After step S3 , in step S4 , the method includes determining that a network energy saving, NES, mode of at least one of the source cell and the target cell has changed or is expected to change.

[0080] It should be understood that a "change in NES mode" of a cell includes a change in the cell from one NES mode to another NES mode (such as the NES modes shown in Table 1), or a change from not operating according to the NES mode ("NES mode off" state) to operating according to the NES mode ("NES mode on" state), or a change from operating according to the NES mode ("NES mode on" state) to not operating according to the NES mode ("NES mode off" state). An example of the "NES mode off" state is when the cell is "on" and not operating according to the NES mode. An example of the "NES mode on" state is when the cell is in an NES mode in which the cell is off and no uplink or downlink data transmission is being performed. Another example of the "NES mode on" state is when the cell is operating according to any of the NES modes shown in Table 1.

[0081] The source infrastructure device may determine that the NES mode of the source cell has changed or is expected to change, or that the NES mode of the target cell has changed or is expected to change, or that the NES modes of both the source cell and the target cell have changed or are expected to change.

[0082] In some embodiments, the source infrastructure device may determine that the NES mode of at least one of the source cell and the target cell has changed (i.e., has been changed). For example, the source infrastructure device may determine that the NES mode of the source cell has changed. In some embodiments, the source infrastructure device may determine that the NES mode of the target cell has changed based on an indication received from the target infrastructure device (e.g., via an Xn interface) that the NES mode of the target cell has changed. In some embodiments, the source infrastructure device may determine that the NES mode of the target cell has changed because it received an indication from the target infrastructure device that the target cell has changed from operating according to an NES mode-off state to operating according to an NES mode-on state.

[0083] In some embodiments, the source infrastructure device may determine that the NES mode of at least one of the source cell and the target cell is expected to change (i.e., at a certain point in the future). For example, the source infrastructure device may determine that the NES mode of the source cell is to be changed, and in response to the determination, the source infrastructure device may transmit an evaluation trigger signal. In another example, the source infrastructure device may determine that the NES mode of the target cell is expected to change based on an indication of an expected change in the NES mode of the target cell received from the target infrastructure device. For example, the target infrastructure device may determine that the NES mode of the target cell is to be changed, and transmit an indication to the source infrastructure device that the NES mode of the target cell is to be changed. In one example, the source infrastructure device may determine that the NES mode of the target cell is expected to change because it receives an indication from the target infrastructure device that the target cell is to change from operating according to the NES mode off state to operating according to the NES mode on state.

[0084] After step S4, in step S5, the method includes, in response, transmitting an evaluation trigger signal to the communication device. The evaluation trigger signal instructs the communication device to evaluate one or more of the conditions that trigger handover of the communication device from the source cell to the target cell.

[0085] In some embodiments, the evaluation trigger signal specifically indicates one or more of the conditions that should be evaluated by the communication device. For example, the evaluation trigger signal may indicate to the communication device that a subset of the conditions indicated to the communication device by the source infrastructure device in step S3 should be evaluated. For example, in step S3, the indication of one or more conditions received from the source infrastructure device may indicate a plurality of conditions identified by "Index 1" and "Index 2," respectively. Then, in step S5, the evaluation trigger signal may indicate that the condition identified by Index 1 should be evaluated by the communication device. In other examples, the evaluation trigger signal indicates to the communication device that all of the conditions indicated to the communication device by the source infrastructure device in step S3 should be evaluated.

[0086] In some embodiments, the evaluation trigger signal may include an indication of the NES mode of at least one of the source cell and the target cell. For example, one of the conditions may be that if the target cell is in a light sleep NES mode, the communications device should be handed over to the target cell. In this example, the evaluation trigger signal indicating to the communications device that the condition is to be evaluated also indicates to the communications device that the NES mode of the target cell has changed or will change to a light sleep NES mode.

[0087] In some embodiments, the target infrastructure device determines that the NES mode of the target cell has changed or is about to change and transmits an indication to the source infrastructure device to transmit an evaluation trigger signal to the communication device. Thus, the source infrastructure device determines that the NES mode of the target cell is expected to change based on the indication received from the target infrastructure device to transmit the evaluation trigger signal. In this case, this determination is implicit, as the indication of transmitting the evaluation trigger signal may not include an explicit indication that the target cell has changed or is expected to change. In some embodiments, the indication of transmitting the evaluation trigger signal to the communication device is transmitted via an Xn interface between the source infrastructure device and the target infrastructure device. In such embodiments, the target infrastructure device effectively triggers the communication device to evaluate one or more conditions. In one example, the target infrastructure device may determine that the NES mode of the target cell has changed because the target cell has changed from operating according to an NES mode on state to an NES mode off state. For example, the target cell may have been awakened by a communication device in the target cell transmitting a wake-up signal to the target infrastructure device. Therefore, when the target cell changes to the NES mode off state, the target infrastructure device can effectively prompt the communication device to switch to the target cell.

[0088] In some embodiments, the source infrastructure device may transmit handover assistance information to the target infrastructure device. The target infrastructure device may determine an instruction to transmit an evaluation trigger signal to the source infrastructure device based on a change or expected change in the NES mode of the target cell and the handover assistance information. In response, the target infrastructure device may then transmit the evaluation trigger signal to the source infrastructure device. The handover assistance information may include one or more of the following: the number of communication devices in the source cell that are candidates for handover to the target cell, the quality of service required by the communication devices, the services required by the communication devices, and the traffic required by the communication devices.

[0089] In some embodiments, the evaluation trigger signal is an RRC signal dedicated to the communication device. In some embodiments, the evaluation trigger signal is a multicast RRC signal received by multiple communication devices in the source cell. In this case, the multicast RRC signal includes a group-common (GC) radio network temporary identifier (RNTI) for identifying the multiple communication devices in the source cell.

[0090] In some embodiments, the evaluation trigger signal is a medium access control (MAC) signal dedicated to the communication device. In some embodiments, the evaluation trigger signal is a multicast MAC signal received by multiple communication devices in the source cell. In this case, the multicast MAC signal includes a GC-RNTI for identifying the multiple communication devices in the source cell.

[0091] In some embodiments, the evaluation trigger signal is a MAC Control Element CE signal.

[0092] In some embodiments, the evaluation trigger signal is a broadcast signal received by a plurality of communication devices in the source cell.

[0093] In some embodiments, the evaluation trigger signal is included in a group-common DCI received by the plurality of communication devices in the source cell, the group-common DCI including a GC-RNTI for identifying the plurality of communication devices in the source cell.

[0094] The method ends in step S6.

[0095] Figure 6 A method for operating a communication device in conditional handover according to an exemplary embodiment is shown in FIG. The method starts at step S11 .

[0096] After step S11 , in step S12 , the method comprises receiving from a source infrastructure equipment of the wireless communication network one or more conditions triggering handover of the communication device from a source cell provided by the source infrastructure equipment to a target cell provided by a target infrastructure of the wireless communication network.

[0097] After step S12, in step S13, the method includes receiving an evaluation trigger signal from the source infrastructure device, the evaluation trigger signal instructing the communication device to evaluate one or more of the conditions that trigger a handover of the communication device from the source cell to the target cell. The evaluation trigger signal is received by the communication device from the source infrastructure device in response to a change or anticipated change in a network energy saving (NES) mode of at least one of the source cell and the target cell.

[0098] Following step S13, in step S14 the method comprises, in response, evaluating one or more of the conditions that trigger handover of the communication device from the source cell to the target cell.

[0099] Following step S14 , in step S15 , the method comprises determining that one or more of the evaluated conditions have been met.

[0100] After step S15, in step S16 the method comprises, in response, initiating handover of the communication device from the source cell to the target cell.

[0101] Initiating a handover may involve detaching from a wireless access interface or wireless link provided by the source infrastructure device and attaching to a wireless access interface or wireless link provided by the target infrastructure device. Initiating a handover may include establishing a wireless connection with the target relay infrastructure device. For example, the communication device may initiate an access procedure with the target infrastructure device. In one example, the communication device may initiate a random access channel (RACH) procedure with the target infrastructure device.

[0102] The method ends in step S17.

[0103] As mentioned above Figure 5 and Figure 6As described, the source infrastructure device transmits an evaluation trigger signal to the communication device, and in response, the communication device evaluates one or more of the conditions. The communication device then determines that the conditions have been met and initiates a handover. Thus, embodiments allow a wireless communication network, aware of changes or anticipated changes in the NES mode, to control when the communication device evaluates the conditions. Because the communication device evaluates one or more of the conditions in response to receiving the evaluation trigger signal (rather than the periodic or continuous evaluation characteristic of conventional conditional handovers), fewer condition evaluations are expected before a positive evaluation result is reached (i.e., determining that one or more of the conditions are met), thereby reducing energy consumption in the wireless communication network. Furthermore, transmitting the evaluation trigger signal in response to determining that the NES mode of at least one of the source cell and the target cell has changed or is anticipated to change means that the communication device can switch cells (or remain in a cell) in response to the change or anticipated change in the NES mode. The wireless communication network can efficiently control which communication devices are in which cells in response to changes in the NES mode according to, for example, a network planning policy.

[0104] Evaluating stop signals

[0105] In some embodiments, an evaluation trigger signal is transmitted by the source infrastructure equipment to the communication device to instruct the communication device to evaluate one or more conditions, and a second subsequent signal (referred to herein as an "evaluation stop signal") is transmitted by the source infrastructure equipment to the communication device to instruct the communication device to stop evaluating the one or more conditions.

[0106] In some embodiments, the source infrastructure device may transmit an evaluation stop signal to the communication device in response to another change in the NES mode of at least one of the source cell and the target cell. For example, the source infrastructure device may transmit an evaluation trigger signal to the communication device in response to determining that the target cell has changed from an "NES mode on" state to an "NES mode off" state. Then, in response to a later determination that the target cell has changed from an "NES mode off" state to an "NES mode on" state, the source infrastructure device may transmit an evaluation stop signal to the communication device.

[0107] Reference to transmitting the evaluation stop signal in response to "another change in the NES mode of at least one of the source cell and the target cell" includes the following cases:

[0108] - transmitting an evaluation trigger signal in response to a change or an expected change in the NES mode of the source cell, and transmitting an evaluation stop signal in response to a change or an expected change in the NES mode of the source cell,

[0109] - transmitting an evaluation trigger signal in response to a change or an expected change in the NES mode of the target cell, and transmitting an evaluation stop signal in response to a change or an expected change in the NES mode of the target cell,

[0110] - transmitting an evaluation trigger signal in response to a change or anticipated change in the NES mode of the source cell, and transmitting an evaluation stop signal in response to a change or anticipated change in the NES mode of the target cell, and

[0111] - transmitting an evaluation trigger signal in response to a change or expected change in the NES mode of the target cell, and transmitting an evaluation stop signal in response to a change or expected change in the NES mode of the source cell.

[0112] In some implementations, the evaluation stop signal may be transmitted based on the expiration of a preconfigured timer.

[0113] Thus, the evaluation trigger signal and the evaluation stop signal can be used to activate and deactivate the evaluation of one or more conditions, respectively. In some embodiments, one or both of the evaluation trigger signal and the evaluation stop signal can be transmitted as a MAC CE. Since the MAC layer is closer to the physical layer than higher layers (such as the RRC layer), the use of a MAC CE allows for fast transmission, and the evaluation trigger signal and the evaluation stop signal therefore allow for fast activation and deactivation of the evaluation of one or more conditions.

[0114] Evaluating restart signals

[0115] In some embodiments, the source infrastructure equipment transmits another signal (referred to herein as an "evaluation restart signal") subsequent to the evaluation stop signal to the communication device to instruct the communication device to restart the evaluation of one or more conditions.

[0116] In some embodiments, the source infrastructure device may transmit an evaluation restart signal to the communication device in response to another change in the NES mode of at least one of the source cell and the target cell. For example, the source infrastructure device may transmit an evaluation stop signal to the communication device in response to determining that the target cell has changed from an "NES mode off" state to an "NES mode on" state. Then, in response to a later determination that the target cell has changed from an "NES mode on" state to an "NES mode off" state, the source infrastructure device may transmit an evaluation restart signal to the communication device.

[0117] Reference to transmitting an evaluation restart signal in response to “a further change in the NES mode of at least one of the source cell and the target cell” includes the following cases:

[0118] - transmitting an evaluation stop signal in response to a change or an expected change in the NES mode of the source cell, and transmitting an evaluation restart signal in response to a change or an expected change in the NES mode of the source cell,

[0119] - transmitting an evaluation stop signal in response to a change or an expected change in the NES mode of the target cell, and transmitting an evaluation restart signal in response to a change or an expected change in the NES mode of the target cell,

[0120] - transmitting an evaluation stop signal in response to a change or anticipated change in the NES mode of the source cell, and transmitting an evaluation restart signal in response to a change or anticipated change in the NES mode of the target cell, and

[0121] - transmitting an evaluation stop signal in response to a change or expected change of the NES mode of the target cell, and transmitting an evaluation restart signal in response to a change or expected change of the NES mode of the source cell.

[0122] In some implementations, the evaluation restart signal may be transmitted based on the expiration of a preconfigured timer.

[0123] Therefore, the evaluation restart signal can be used to reactivate the evaluation of one or more conditions. In some embodiments, the evaluation restart signal can be transmitted as a MAC CE. Since the MAC layer is closer to the physical layer than higher layers (such as the RRC layer), the use of a MAC CE allows for fast transmission, and the evaluation restart signal allows for fast reactivation of the evaluation of one or more conditions.

[0124] In an example, a wireless communication network may include multiple candidate target cells (e.g., three candidate target cells). The candidate target cells may be provided by the same or different target infrastructure devices. The source infrastructure device may configure a communication device in the source cell provided by the source infrastructure device using a configuration for each of the multiple candidate target cells. For example, the communication device may be configured with a configuration such as: measurements and / or conditions for handover to each of the multiple candidate target cells.

[0125] In conventional conditional handover, a communications device may evaluate the handover conditions of each of a plurality of candidate target cells and handover to the candidate target cell for which the handover conditions are met (eg, because a threshold of an event has been met).

[0126] However, according to an exemplary embodiment, based on the NES mode of the candidate target cell, the communications device may or may not evaluate the handover conditions for the candidate target cell. For example, the first and second target cells among the multiple candidate target cells may not be in NES mode, while the third target cell among the multiple target cells may be in NES mode (e.g., the third target cell may be turned off). According to an exemplary embodiment, the communications device may be evaluating the conditions for handover to the first and second target cells. However, the communications device may determine that the conditions for handover to the first and second target cells are not met. In some cases, the communications device is continuously evaluating the handover conditions for the first and second target cells. If the handover conditions are not met, the evaluation may continue for a period of time. At a later stage, the NES mode of the third target cell may change. For example, the third target cell may be turned on. According to an exemplary embodiment, the source infrastructure device may determine that the NES mode of the third target cell has changed and, in response, transmit a signal to the communications device indicating that the conditions for handover to the third target cell are to be evaluated. The communications device may then evaluate the conditions for handover to the first target cell, the conditions for handover to the second target cell, and the conditions for handover to the third target cell. The communications device will handover to the target cell whose handover conditions are first met. Thus, in some examples, the communications device may handover to the second target cell, and in other examples, the communications device may handover to the first target cell, and in other examples, the communications device may handover to the third target cell. In some examples, the communications device evaluates the conditions for handover to the third target cell rather than the conditions for handover to the first and second target cells because the indication to evaluate the conditions for the third target cell is received later.

[0127] Example switching conditions

[0128] As explained above, the source infrastructure equipment configures one or more conditions for the communication device that, if met, cause the communication device to be handed over from the source cell to the target cell. The following are other examples of such conditions:

[0129] If the source cell has changed or is expected to change to an NES mode-on state (e.g., to a deep sleep NES mode or a cell-off state), the communication device will be handed over from the source cell to the target cell. In an example, the source infrastructure equipment may transmit an evaluation trigger signal to the communication device after determining that the NES mode of the source cell has changed. In this way, the source infrastructure equipment can promote network energy conservation by entering the NES mode-on state and thereby offloading its communication device to the target cell.

[0130] If the target cell has changed or is expected to change to an NES mode-off state or a low-power NES mode (e.g., to a relatively high-power NES mode, such as a light sleep NES mode), the communication device will be switched from the source cell to the target cell. In an example, the source infrastructure equipment may transmit an evaluation trigger signal to the communication device after determining that the NES mode of the target cell has changed. In this manner, when the target infrastructure equipment switches to an NES mode-off state or a low-power NES mode, the target infrastructure equipment is able to accept the new communication device.

[0131] If the source cell has changed or is expected to change to an NES mode-off state or a low-power NES mode (e.g., to a relatively high-power NES mode, such as a light sleep NES mode), the communication device will be handed over from the source cell to the target cell. In an example, the source infrastructure equipment may transmit an evaluation trigger signal to the communication device after determining that the NES mode of the source cell has changed. In this example, the communication device, which preferably operates in NES mode-on, may be offloaded to the target cell to promote energy conservation.

[0132] If the target cell has changed or is expected to change to an NES mode-on state (e.g., to a deep sleep NES mode), the communication device will be handed over from the source cell to the target cell. In an example, the source infrastructure equipment may transmit an evaluation trigger signal to the communication device after determining that the NES mode of the target cell has changed. In this way, the target infrastructure equipment can accept a new communication device that prefers to operate in the NES mode-on state to promote energy conservation.

[0133] It should be understood that while the present disclosure in some aspects focuses on implementations in LTE and / or 5G networks for the sake of providing specific examples, the same principles can be applied to other wireless telecommunication systems. Therefore, even though the terminology used herein is generally the same or similar to that of the LTE and 5G standards, the teachings are not limited to current versions of LTE and 5G and can be equally applied to any suitable arrangements that are not based on LTE or 5G and / or do not conform to any other future versions of LTE, 5G, or other standards.

[0134] It should be noted that the various exemplary methods discussed herein may rely on predetermined / predefined information in a sense that is known to both the base station and the communication device. It should be understood that such predetermined / predefined information may generally be established, for example, by definition in the operating standard of the wireless telecommunications system, or in signaling previously exchanged between the base station and the communication device (e.g., in system information signaling), or associated with radio resource control setup signaling, or in information stored in a SIM application. That is, the specific manner in which the relevant predefined information is established and shared between the various elements of the wireless telecommunications system is not of primary significance to the operating principles described herein. It should be further noted that the various exemplary methods discussed herein rely on information exchanged / transmitted between the various elements of the wireless telecommunications system, and it should be understood that such communication may generally be conducted according to conventional techniques, such as in terms of the specific signaling protocol and type of communication channel used, unless the context requires otherwise. That is, the specific manner in which the relevant information is exchanged between the various elements of the wireless telecommunications system is not of primary significance to the operating principles described herein.

[0135] It should be understood that the principles described herein are applicable not only to specific types of communication devices, but may be more generally applied to any type of communication device. For example, the method is not limited to URLLC / IIoT devices or other low-latency communication devices, but may be more generally applied to any type of communication device that operates, for example, using a wireless link to a communication network.

[0136] It should be further understood that the principles described herein are applicable not only to LTE-based or 5G / NR-based wireless telecommunication systems, but also to any type of wireless telecommunication system that supports dynamic scheduling of shared communication resources.

[0137] Further particular and preferred aspects of the invention are set out in the accompanying independent and dependent claims.It will be appreciated that features of the dependent claims may be combined with features of the independent claims in combinations other than those explicitly set out in the claims.

[0138] Therefore, the foregoing discussion discloses and describes only exemplary embodiments of the present invention. As will be appreciated by those skilled in the art, the present invention may be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, the disclosure of the present invention is intended to be illustrative, not limiting, of the scope of the present invention and the scope of the other claims. The present disclosure (including any readily discernible variations of the teachings herein) defines, in part, the scope of the aforementioned claim terms such that no inventive subject matter is dedicated to the public.

[0139] The corresponding features of the disclosure are defined by the following numbered paragraphs:

[0140] Paragraph 1. A method of operating a source infrastructure device of a wireless communication network in a conditional handover, the method comprising:

[0141] configuring one or more conditions that trigger handover of a communication device from a source cell provided by a source infrastructure device to a target cell provided by a target infrastructure device of a wireless communication network,

[0142] transmitting to the communication device an indication of one or more conditions that trigger a handover of the communication device from a source cell to a target cell,

[0143] determining that a network energy saving (NES) mode of at least one of the source cell and the target cell has changed or is expected to change, and in response,

[0144] An evaluation trigger signal is transmitted to the communication device, the evaluation trigger signal instructing the communication device to evaluate one or more of the conditions that trigger a handover of the communication device from the source cell to the target cell.

[0145] Paragraph 2. The method according to paragraph 1, comprising:

[0146] An evaluation stop signal is transmitted that indicates to the communication device to stop evaluating one or more conditions that trigger handover of the communication device from the source cell to the target cell.

[0147] Paragraph 3. The method according to paragraph 2, comprising:

[0148] An evaluation restart signal is transmitted that instructs the communication device to restart evaluating one or more conditions that trigger handover of the communication device from the source cell to the target cell.

[0149] Paragraph 4. The method according to paragraph 3, wherein one or more of the evaluation trigger signal, the evaluation stop signal and the evaluation restart signal is transmitted in a medium access control MAC control element CE.

[0150] Paragraph 5. A method according to any of paragraphs 1 to 4, wherein the evaluation trigger signal comprises an indication of a NES mode of at least one of the source cell and the target cell.

[0151] Paragraph 6. A method according to any of paragraphs 1 to 4, wherein the evaluation trigger signal is a radio resource control (RRC) signal dedicated to the communication device.

[0152] Paragraph 7. A method according to any one of paragraphs 1 to 4, wherein the evaluation trigger signal is a multicast radio resource control (RRC) signal received by multiple communication devices in a source cell, the multicast RRC signal including a group common (GC) radio network temporary identifier (RNTI) for identifying the multiple communication devices in the source cell.

[0153] Paragraph 8. The method of any of paragraphs 1 to 4, wherein the evaluation trigger signal is a medium access control (MAC) signal specific to the communication device.

[0154] Paragraph 9. A method according to any one of paragraphs 1 to 4, wherein the evaluation trigger signal is a multicast medium access control MAC signal received by multiple communication devices in the source cell, and the multicast MAC signal includes a group common GC radio network temporary identifier RNTI for identifying the multiple communication devices in the source cell.

[0155] Paragraph 10. A method according to any of paragraphs 1 to 4, wherein the evaluation trigger signal is a broadcast signal received by a plurality of communication devices in the source cell.

[0156] Paragraph 11. A method according to any one of paragraphs 1 to 4, wherein the evaluation trigger signal is included in group common downlink control information DCI received by multiple communication devices in the source cell, and the group common DCI includes a group common GC radio network temporary identifier RNTI for identifying the multiple communication devices in the source cell.

[0157] Paragraph 12. A method according to any of paragraphs 1 to 11, wherein determining that an NES mode of at least one of the source cell and the target cell has changed or is expected to change comprises:

[0158] An indication is received from the target infrastructure device that the NES mode of the target cell has changed or is expected to change.

[0159] Paragraph 13. The method of Paragraph 12, wherein the indication that the NES mode of the target infrastructure device has changed is transmitted via an Xn interface between the source infrastructure device and the target infrastructure device.

[0160] Paragraph 14. A method according to any of paragraphs 1 to 11, wherein determining that the NES mode of at least one of the source cell and the target cell has changed or is expected to change comprises:

[0161] An indication is received from the target infrastructure equipment to transmit an evaluation trigger signal to the communication device in response to a change or anticipated change in the NES mode of the target cell.

[0162] Paragraph 15. The method according to paragraph 14, comprising:

[0163] Handover assistance information is transmitted to the target infrastructure equipment, the handover assistance information including one or more of the following: the number of communication devices in the source cell that are candidates for handover to the target cell, the quality of service required by the communication devices, the service required by the communication devices, and the traffic required by the communication devices.

[0164] Paragraph 16. A method of operating a communication device in conditional handover, the method comprising:

[0165] receiving, from source infrastructure equipment of the wireless communication network, an indication of one or more conditions that trigger handover of the communication device from a source cell provided by the source infrastructure equipment to a target cell provided by a target infrastructure of the wireless communication network,

[0166] receiving an evaluation trigger signal from a source infrastructure device, the evaluation trigger signal instructing the communication device to evaluate one or more of the conditions that trigger a handover of the communication device from the source cell to the target cell, the evaluation trigger signal being received by the communication device from the source infrastructure device in response to a change or anticipated change in a network energy saving (NES) mode of at least one of the source cell and the target cell, and in response,

[0167] One or more of the conditions that trigger handover of the communication device from the source cell to the target cell are evaluated.

[0168] determining that one or more of the evaluated conditions have been satisfied, and in response, and

[0169] Initiate handover of a communication device from a source cell to a target cell.

[0170] Paragraph 17. The method according to paragraph 16, comprising:

[0171] An evaluation stop signal is received, the evaluation stop signal indicating to the communication device to stop evaluating one or more conditions that trigger handover of the communication device from the source cell to the target cell.

[0172] Paragraph 18. The method according to paragraph 16, comprising:

[0173] An evaluation restart signal is received, the evaluation restart signal instructing the communication device to restart evaluating one or more conditions that trigger handover of the communication device from the source cell to the target cell.

[0174] Paragraph 19. The method of paragraph 18, wherein one or more of the evaluation trigger signal, the evaluation stop signal, and the evaluation restart signal is received in a medium access control MAC control element CE.

[0175] Paragraph 20. A method according to any of paragraphs 16 to 19, wherein the evaluation trigger signal comprises an indication of a NES mode of at least one of the source cell and the target cell.

[0176] Paragraph 21. A method according to any of paragraphs 16 to 20, wherein the evaluation trigger signal is a Radio Resource Control (RRC) signal dedicated to the communication device.

[0177] Paragraph 22. A method according to any one of paragraphs 16 to 20, wherein the evaluation trigger signal is a multicast radio resource control RRC signal received by multiple communication devices in the source cell, and the multicast RRC signal includes a group common GC radio network temporary identifier RNTI for identifying the multiple communication devices in the source cell.

[0178] Paragraph 23. The method of any of paragraphs 16 to 20, wherein the evaluation trigger signal is a medium access control (MAC) signal specific to the communication device.

[0179] Paragraph 24. A method according to any one of paragraphs 16 to 20, wherein the evaluation trigger signal is a multicast medium access control MAC signal received by multiple communication devices in the source cell, and the multicast MAC signal includes a group common GC radio network temporary identifier RNTI for identifying the multiple communication devices in the source cell.

[0180] Paragraph 25. A method according to any of paragraphs 16 to 20, wherein the evaluation trigger signal is a broadcast signal received by a plurality of communication devices in the source cell.

[0181] Paragraph 26. A method according to any one of paragraphs 16 to 20, wherein the evaluation trigger signal is included in group common downlink control information DCI received by multiple communication devices in the source cell, the group common DCI including a group common GC radio network temporary identifier RNTI for identifying the multiple communication devices in the source cell.

[0182] Paragraph 27. A source infrastructure device of a wireless communication network for use in conditional handover, the source infrastructure device comprising:

[0183] a transmitter configured to transmit a signal;

[0184] a receiver configured to receive a signal;

[0185] The controller, together with the transmitter and receiver, is configured to:

[0186] configuring one or more conditions that trigger handover of a communication device from a source cell provided by a source infrastructure device to a target cell provided by a target infrastructure device of a wireless communication network,

[0187] transmitting to the communication device an indication of one or more conditions that trigger a handover of the communication device from a source cell to a target cell,

[0188] determining that a network energy saving (NES) mode of at least one of the source cell and the target cell has changed or is expected to change, and in response,

[0189] An evaluation trigger signal is transmitted to the communication device, the evaluation trigger signal instructing the communication device to evaluate one or more of the conditions that trigger a handover of the communication device from the source cell to the target cell.

[0190] Paragraph 28. A communication device for use in conditional switching, the communication device comprising:

[0191] a transmitter configured to transmit a signal;

[0192] a receiver configured to receive a signal;

[0193] The controller, together with the transmitter and receiver, is configured to:

[0194] receiving, from source infrastructure equipment of the wireless communication network, an indication of one or more conditions that trigger handover of the communication device from a source cell provided by the source infrastructure equipment to a target cell provided by a target infrastructure of the wireless communication network,

[0195] receiving an evaluation trigger signal from a source infrastructure device, the evaluation trigger signal instructing the communication device to evaluate one or more of the conditions that trigger a handover of the communication device from the source cell to the target cell, the evaluation trigger signal being received by the communication device from the source infrastructure device in response to a change or anticipated change in a network energy saving (NES) mode of at least one of the source cell and the target cell, and in response,

[0196] evaluating one or more of the conditions that trigger handover of the communication device from the source cell to the target cell,

[0197] determining that one or more of the evaluated conditions have been satisfied, and in response, and

[0198] Initiate handover of the communication device from a source cell to a target cell.

[0199] Paragraph 29. Circuitry of a source infrastructure device of a wireless communication network for use in a conditional handoff, the circuitry comprising:

[0200] A transmitter circuit system configured to transmit a signal,

[0201] a receiver circuit system configured to receive a signal;

[0202] The controller circuitry, together with the transmitter circuitry and the receiver circuitry, is configured to:

[0203] configuring one or more conditions that trigger handover of a communication device from a source cell provided by a source infrastructure device to a target cell provided by a target infrastructure device of a wireless communication network,

[0204] transmitting to the communication device an indication of one or more conditions that trigger a handover of the communication device from a source cell to a target cell,

[0205] determining that a network energy saving (NES) mode of at least one of the source cell and the target cell has changed or is expected to change, and in response,

[0206] An evaluation trigger signal is transmitted to the communication device, the evaluation trigger signal instructing the communication device to evaluate one or more of the conditions that trigger a handover of the communication device from the source cell to the target cell.

[0207] Paragraph 30. A circuit system for a communication device for use in conditional switching, the circuit system comprising:

[0208] A transmitter circuit system configured to transmit a signal,

[0209] a receiver circuit system configured to receive a signal;

[0210] The controller circuitry, together with the transmitter circuitry and the receiver circuitry, is configured to:

[0211] receiving, from source infrastructure equipment of the wireless communication network, an indication of one or more conditions that trigger handover of the communication device from a source cell provided by the source infrastructure equipment to a target cell provided by a target infrastructure of the wireless communication network,

[0212] receiving an evaluation trigger signal from a source infrastructure device, the evaluation trigger signal instructing the communication device to evaluate one or more of the conditions that trigger a handover of the communication device from the source cell to the target cell, the evaluation trigger signal being received by the communication device from the source infrastructure device in response to a change or anticipated change in a network energy saving (NES) mode of at least one of the source cell and the target cell, and in response,

[0213] evaluating one or more of the conditions that trigger handover of the communication device from the source cell to the target cell,

[0214] determining that one or more of the evaluated conditions have been satisfied, and in response, and

[0215] Initiate handover of a communication device from a source cell to a target cell.

[0216] Paragraph 31. A wireless communication network comprising a source infrastructure device according to Paragraph 27 and a communication apparatus according to Paragraph 28.

[0217] Paragraph 32. A computer program comprising instructions which, when loaded onto a computer, cause the computer to perform a method according to any one of paragraphs 1 to 26.

[0218] Paragraph 33. A non-transitory computer-readable storage medium storing a computer program according to Paragraph 32.

[0219] References

[0220] [1] RP-182090, “Revised SID: Study on NR Industrial Internet of Things (IoT),” 3GPP RAN#81.

[0221] [2]Holma H. and Toskala A, "LTE for UMTS OFDMAand SC-FDMA based radioaccess", John Wiley and Sons, 2009.

[0222] [3]TS38.300 V16.5.0, "NG and NR-RAN Overall Description", Release16.

[0223] [4]RP-213554, “Study on network energy savings for NR”.

[0224] [5]TR38.840, "Study on User Equipment (UE) power saving in NR", Release16.

[0225] [6]TR38.864, "Study on network energy savings for NR", Release 18.

[0226] [7]R2-2213040, "Post RAN2#120TP for TR 38.864", Release 18.

Claims

1. A method of operating a source infrastructure device of a wireless communication network in a conditional handover, the method comprising: configuring one or more conditions that trigger handover of a communication device from a source cell provided by the source infrastructure equipment to a target cell provided by a target infrastructure equipment of the wireless communication network, transmitting to the communication device an indication of the one or more conditions that trigger a handover of the communication device from the source cell to the target cell, determining that a network energy saving (NES) mode of at least one of the source cell and the target cell has changed or is expected to change, and in response, An evaluation trigger signal is transmitted to the communication device, the evaluation trigger signal instructing the communication device to evaluate one or more of the conditions that trigger handover of the communication device from the source cell to the target cell.

2. The method according to claim 1, comprising: An evaluation stop signal is transmitted, the evaluation stop signal indicating to the communication device to stop evaluating the one or more conditions that trigger handover of the communication device from the source cell to the target cell.

3. The method according to claim 2, comprising: An evaluation restart signal is transmitted, the evaluation restart signal instructing the communication device to restart evaluating the one or more conditions that trigger handover of the communication device from the source cell to the target cell.

4. The method according to claim 3, wherein: One or more of the evaluation trigger signal, the evaluation stop signal and the evaluation restart signal are transmitted in a Medium Access Control MAC Control Element CE.

5. The method according to claim 1, wherein The evaluation trigger signal includes an indication of an NES mode of at least one of the source cell and the target cell.

6. The method according to claim 1, wherein The evaluation trigger signal is a radio resource control (RRC) signal dedicated to the communication device.

7. The method according to claim 1, wherein The evaluation trigger signal is a multicast radio resource control (RRC) signal received by a plurality of communication devices in the source cell, and the multicast RRC signal includes a group-common (GC) radio network temporary identifier (RNTI) for identifying the plurality of communication devices in the source cell.

8. The method according to claim 1, wherein The evaluation trigger signal is a medium access control MAC signal dedicated to the communication device.

9. The method according to claim 1, wherein The evaluation trigger signal is a multicast medium access control (MAC) signal received by a plurality of communication devices in the source cell, and the multicast MAC signal includes a group common (GC) radio network temporary identifier (RNTI) for identifying the plurality of communication devices in the source cell.

10. The method according to claim 1, wherein The evaluation trigger signal is a broadcast signal received by a plurality of communication devices in the source cell.

11. The method according to claim 1, wherein The evaluation trigger signal is included in group common downlink control information (DCI) received by a plurality of communication devices in the source cell, the group common DCI including a group common GC radio network temporary identifier (RNTI) for identifying the plurality of communication devices in the source cell.

12. The method according to claim 1, wherein Determining that the NES mode of at least one source cell and the target cell has changed or is expected to change includes: An indication is received from the target infrastructure equipment that the NES mode of the target cell has changed or is expected to change.

13. The method according to claim 12, wherein: The indication that the NES mode of the target infrastructure device has changed is transmitted via an Xn interface between the source infrastructure device and the target infrastructure device.

14. The method according to claim 1, wherein Determining that the NES mode of at least one of the source cell and the target cell has changed or is expected to change includes: An indication is received from the target infrastructure equipment to transmit the evaluation trigger signal to the communication device in response to a change or anticipated change in the NES mode of the target cell.

15. The method according to claim 14, comprising: Transmitting handover assistance information to the target infrastructure equipment, the handover assistance information including one or more of the following: the number of communication devices in the source cell that are candidates for handover to the target cell, the quality of service required by the communication devices, the service required by the communication devices, and the traffic required by the communication devices.

16. A method for operating a communication device in conditional switching, the method comprising: receiving, from source infrastructure equipment of a wireless communication network, an indication of one or more conditions triggering handover of the communication device from a source cell provided by the source infrastructure equipment to a target cell provided by a target infrastructure of the wireless communication network, receiving an evaluation trigger signal from the source infrastructure equipment, the evaluation trigger signal instructing the communication device to evaluate one or more of the conditions that trigger a handover of the communication device from the source cell to the target cell, the evaluation trigger signal being received by the communication device from the source infrastructure equipment in response to a change or anticipated change in a network energy saving (NES) mode of at least one of the source cell and the target cell, and in response, evaluating one or more of the conditions that trigger handover of the communication device from the source cell to the target cell, determining that one or more of the conditions evaluated have been satisfied, and in response, and Initiating a handover of the communication device from the source cell to the target cell.

17. The method according to claim 16, comprising: An evaluation stop signal is received, the evaluation stop signal indicating to the communication device to stop evaluating the one or more conditions that trigger handover of the communication device from the source cell to the target cell.

18. The method according to claim 16, comprising: An evaluation restart signal is received, the evaluation restart signal instructing the communication device to restart evaluating the one or more conditions that trigger handover of the communication device from the source cell to the target cell.

19. The method according to claim 18, wherein One or more of the evaluation trigger signal, the evaluation stop signal and the evaluation restart signal are received in a Medium Access Control MAC Control Element CE.

20. The method according to claim 16, wherein The evaluation trigger signal includes an indication of an NES mode of at least one of the source cell and the target cell.

21. The method according to claim 16, wherein The evaluation trigger signal is a radio resource control (RRC) signal dedicated to the communication device.

22. The method according to claim 16, wherein The evaluation trigger signal is a multicast radio resource control (RRC) signal received by a plurality of communication devices in the source cell, and the multicast RRC signal includes a group-common (GC) radio network temporary identifier (RNTI) for identifying the plurality of communication devices in the source cell.

23. The method according to claim 16, wherein The evaluation trigger signal is a medium access control MAC signal dedicated to the communication device.

24. The method according to claim 16, wherein The evaluation trigger signal is a multicast medium access control (MAC) signal received by a plurality of communication devices in the source cell, and the multicast MAC signal includes a group common (GC) radio network temporary identifier (RNTI) for identifying the plurality of communication devices in the source cell.

25. The method according to claim 16, wherein The evaluation trigger signal is a broadcast signal received by a plurality of communication devices in the source cell.

26. The method according to claim 16, wherein The evaluation trigger signal is included in group common downlink control information (DCI) received by a plurality of communication devices in the source cell, the group common DCI including a group common GC radio network temporary identifier (RNTI) for identifying the plurality of communication devices in the source cell.

27. A source infrastructure device of a wireless communication network for use in conditional handover, the source infrastructure device comprising: a transmitter configured to transmit a signal; a receiver configured to receive a signal; A controller, together with the transmitter and the receiver, is configured to: configuring one or more conditions that trigger handover of a communication device from a source cell provided by the source infrastructure equipment to a target cell provided by a target infrastructure equipment of the wireless communication network, transmitting to the communication device an indication of the one or more conditions that trigger a handover of the communication device from the source cell to the target cell, determining that a network energy saving (NES) mode of at least one of the source cell and the target cell has changed or is expected to change, and in response, An evaluation trigger signal is transmitted to the communication device, the evaluation trigger signal instructing the communication device to evaluate one or more of the conditions that trigger handover of the communication device from the source cell to the target cell.

28. A communication device for use in conditional switching, the communication device comprising: a transmitter configured to transmit a signal; a receiver configured to receive a signal; A controller, together with the transmitter and the receiver, is configured to: receiving, from source infrastructure equipment of a wireless communication network, an indication of one or more conditions triggering handover of the communication device from a source cell provided by the source infrastructure equipment to a target cell provided by a target infrastructure of the wireless communication network, receiving an evaluation trigger signal from the source infrastructure equipment, the evaluation trigger signal instructing the communication device to evaluate one or more of the conditions that trigger a handover of the communication device from the source cell to the target cell, the evaluation trigger signal being received by the communication device from the source infrastructure equipment in response to a change or anticipated change in a network energy saving (NES) mode of at least one of the source cell and the target cell, and in response, evaluating one or more of the conditions that trigger handover of the communication device from the source cell to the target cell, determining that one or more of the conditions evaluated have been satisfied, and in response, and Initiating a handover of the communication device from the source cell to the target cell.

29. Circuitry for use in a source infrastructure device of a wireless communication network in a conditional handoff, the circuitry comprising: A transmitter circuit system configured to transmit a signal, a receiver circuit system configured to receive a signal; a controller circuitry, configured with the transmitter circuitry and the receiver circuitry to: configuring one or more conditions that trigger handover of a communication device from a source cell provided by the source infrastructure equipment to a target cell provided by a target infrastructure equipment of the wireless communication network, transmitting to the communication device an indication of the one or more conditions that trigger a handover of the communication device from the source cell to the target cell, determining that a network energy saving (NES) mode of at least one of the source cell and the target cell has changed or is expected to change, and in response, An evaluation trigger signal is transmitted to the communication device, the evaluation trigger signal instructing the communication device to evaluate one or more of the conditions that trigger handover of the communication device from the source cell to the target cell.

30. A circuit system of a communication device for use in conditional switching, the circuit system comprising: A transmitter circuit system configured to transmit a signal, a receiver circuit system configured to receive a signal; a controller circuitry, configured with the transmitter circuitry and the receiver circuitry to: receiving, from source infrastructure equipment of a wireless communication network, an indication of one or more conditions triggering handover of the communication device from a source cell provided by the source infrastructure equipment to a target cell provided by a target infrastructure of the wireless communication network, receiving an evaluation trigger signal from the source infrastructure equipment, the evaluation trigger signal instructing the communication device to evaluate one or more of the conditions that trigger a handover of the communication device from the source cell to the target cell, the evaluation trigger signal being received by the communication device from the source infrastructure equipment in response to a change or anticipated change in a network energy saving (NES) mode of at least one of the source cell and the target cell, and in response, evaluating one or more of the conditions that trigger handover of the communication device from the source cell to the target cell, determining that one or more of the conditions evaluated have been satisfied, and in response, and Initiating a handover of the communication device from the source cell to the target cell.

31. A wireless communication network comprising a source infrastructure device according to claim 27 and a communication apparatus according to claim 28.

32. A computer program comprising instructions which, when loaded onto a computer, cause the computer to perform the method according to claim 1 or claim 16.

33. A non-transitory computer-readable storage medium storing the computer program according to claim 32.

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