SSB measurement time configuration for cell switching terminal device provided by a movable base station / relay

Abstract

Embodiments of the present disclosure provide methods and apparatuses for enhancing SSB measurement time configuration (SMTC) for switching terminal device in communication network A method (300) performed by a terminal device in a communication network comprises: obtaining (S302) a first synchronization signal block measurement timing configuration, SMTC, before or after changing from a first cell to a second cell; adjusting (S304) an offset parameter in the first SMTC, based at least on a propagation delay in the second cell; and performing (S306) measurement in the second cell, based on the first SMTC with the adjusted offset parameter. According to embodiments of the present disclosure, the terminal device can apply STMC properly after being switched to and / or reselecting a cell with different SSB characteristics.

Description

[0001] SSB MEASUREMENT TIME CONFIGURATION FOR CELL SWITCHING TERMINAL DEVICE PROVIDED BY A MOVABLE BASE STATION / RELAY

[0002] TECHNICAL FIELD

[0003] The present disclosure relates generally to the technology of wireless communication, and in particular, to a method and an apparatus for enhancing SSB measurement time configuration (SMTC) for cell switching terminal device in communication network. In particular, when switching cells provided by a movable base station / relay. SSB may refer to a synchronization signal block, which may be a combination of synchronization signal (SS) and physical broadcast channel (PBCH) in the communication network.

[0004] BACKGROUND

[0005] This section introduces aspects that may facilitate better understanding of the present disclosure. Accordingly, the statements of this section are to be read in this light and are not to be understood as admissions about what is in the prior art or what is not in the prior art.

[0006] With the development of requirements for communication services, it is necessary to complement mobile communication networks on the ground by many other kinds of technologies. For example, to some underserved areas where a fix base station is hard to deploy, a movable base station / relay will be an advantageous choice. One example for such movable base station / relay is a satellite communication network.

[0007] When a terminal device is switched from a first cell to a second cell, it is necessary for the terminal device to obtain SSB information of the second cell. Particularly, when any one of the first or the second cell is provided by a movable base station / relay, the SSB signal in the second cell may have different characteristics from the SSB signal in the first cell.

[0008] SUMMARY

[0009] This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

[0010] A moving base station / relay in the network may cause some issues, such as moving cells or switching cells, or propagation delay, etc. Such delay will also influence SSB transmitted to the terminal device served by the network. Different SSB from different cells may have different characteristics. A measurement result obtained by the terminal device will be interfered, or sometimes the measurement result cannot be obtained, if the terminal device cannot understand such difference.

[0011] Certain aspects of the present disclosure and their embodiments may provide solutions to these or other challenges. Specific method and apparatus for enhancing SMTC in communication network are provided.

[0012] A first aspect of the present disclosure provides a method performed by a terminal device in a communication network. The method comprises: obtaining a first synchronization signal block measurement timing configuration, SMTC, before or after changing from a first cell to a second cell; adjusting an offset parameter in the first SMTC, based at least on a propagation delay in the second cell; and performing measurement in the second cell, based on the first SMTC with the adjusted offset parameter.

[0013] In exemplary embodiments of the present disclosure, a first synchronization signal block, SSB, is configured for the first cell, and a second SSB is configured for the second cell; and the first SSB and the second SSB occupy the same time position in schedule, or the first SSB and the second SSB have different SSB indices, or the second SSB is a time shifted version of the first SSB.

[0014] In exemplary embodiments of the present disclosure, the method further comprises: adjusting the offset parameter in the first SMTC, further based on a time offset in schedule between the first SSB and the second SSB.

[0015] In exemplary embodiments of the present disclosure, the offset parameter in the first SMTC is provided by the first cell or the second cell, based on the time offset in schedule between the first SSB and the second SSB.

[0016] In exemplary embodiments of the present disclosure, the method further comprises: performing measurement in the second cell, based on the first SMTC without adjusting the offset parameter based on the propagation delay, in response to an indication from the first cell or the second cell.

[0017] In exemplary embodiments of the present disclosure, the method further comprises: obtaining a second SMTC; and performing measurement, based on the second SMTC.

[0018] In exemplary embodiments of the present disclosure, the method further comprises: transmitting a request for the first SMTC and / or the second SMTC.

[0019] In exemplary embodiments of the present disclosure, the first SMTC is obtained by the terminal device in a common control signaling; and the second SMTC is obtained by the terminal device in a dedicated signaling.

[0020] In exemplary embodiments of the present disclosure, the first SMTC is obtained by the terminal device in a system information block, SIB.

[0021] In exemplary embodiments of the present disclosure, the terminal device obtains the SIB regardless of whether an indication about a change in the SIB exists.

[0022] In exemplary embodiments of the present disclosure, the first SMTC is obtained by the terminal device in a dedicated signaling before the changing; and the second SMTC is obtained by the terminal device in a dedicated signaling after the changing.

[0023] In exemplary embodiments of the present disclosure, an indication from the first cell or the second cell indicates the terminal device at least one of: whether to adjust an offset parameter in the first SMTC based on a propagation delay in the second cell; using the first SMTC to perform measurement in the second cell; or using another SMTC to perform measurement in the second cell; and the indication is implicit or explicit.

[0024] In exemplary embodiments of the present disclosure, the terminal device is in a RRC CONNECTED state in the first cell and switches to the second cell; or the terminal device is in a RRC IDLE state or an INACTIVE state and reselects the second cell.

[0025] In exemplary embodiments of the present disclosure, terminal device changes from the first cell to the second cell without L3 mobility.

[0026] In exemplary embodiments of the present disclosure, the first cell and the second cell have the same physical cell identity.

[0027] In exemplary embodiments of the present disclosure, the first cell is provided by a first satellite and / or the second cell is provided by a second satellite.

[0028] A second aspect of the present disclosure provides a method performed by a network node in a communication network. The method comprises: transmitting, a first synchronization signal block measurement timing configuration, SMTC, to a terminal device, before or after the terminal device changing from a first cell to a second cell; and indicating the terminal device whether to adjust an offset parameter in the first SMTC.

[0029] In exemplary embodiments of the present disclosure, the network node indicates the terminal device whether to adjust the offset parameter in the first SMTC based on a propagation in the second cell; a first synchronization signal block, SSB, is configured for the first cell, and a second SSB is configured for the second cell; and the first SSB and the second SSB occupy the same time position in schedule, or the first SSB and the second SSB have different SSB indices, or the second SSB is a time shifted version of the first SSB.

[0030] In exemplary embodiments of the present disclosure, the method further comprises: providing the offset parameter in the first SMTC, based on the time offset in schedule between the first SSB and the second SSB.

[0031] In exemplary embodiments of the present disclosure, the method further comprises: transmitting, to the terminal device, a second SMTC.

[0032] In exemplary embodiments of the present disclosure, the method further comprises: receiving, from the terminal device, a request for the first SMTC and / or the second SMTC.

[0033] In exemplary embodiments of the present disclosure, the first SMTC is included in a common control signaling; wherein the second SMTC is included in a dedicated signaling.

[0034] In exemplary embodiments of the present disclosure, the first SMTC is included in a system information block, SIB.

[0035] In exemplary embodiments of the present disclosure, the terminal device obtains the SIB regardless of whether an indication about a change in the SIB exists.

[0036] In exemplary embodiments of the present disclosure, the first SMTC is obtained by the terminal device in a dedicated signaling before the changing; and the second SMTC is obtained by the terminal device in a dedicated signaling after the changing.

[0037] In exemplary embodiments of the present disclosure, the terminal device is in a RRC CONNECTED state in the first cell and switches to the second cell; or the terminal device is in a RRC IDLE state or an INACTIVE state and reselects the second cell.

[0038] In exemplary embodiments of the present disclosure, terminal device changes from the first cell to the second cell without L3 mobility.

[0039] In exemplary embodiments of the present disclosure, the first cell and the second cell have the same physical cell identity.

[0040] In exemplary embodiments of the present disclosure, the first cell is provided by a first satellite and / or the second cell is provided by a second satellite; and the network node is a base station connected to the first satellite and / or the second satellite.

[0041] In exemplary embodiments of the present disclosure, the method further comprises: determining whether a condition related to served terminal devices is satisfied; and when the condition is satisfied, performing at least one of the following actions: disabling the changing from the first cell to the second cell, when the second cell has the same PCI with the first cell; configuring a SSB in the first cell to use a different frequency than a SSB in the second cell; configuring the SSB in the second cell to be sent upon or after stopping the SSB in the first cell; or releasing terminal devices served by the network node and not supporting to obtain SSB information about the second cell.

[0042] In exemplary embodiments of the present disclosure, wherein the condition comprises at least one of: a number of RRC CONNECTED terminal devices served by the network node and not supporting to obtain SSB information about the second cell after the changing exceeds a threshold; and / or a ratio of RRC CONNECTED terminal devices served by the network node and not supporting to obtain SSB information about the second cell after the changing exceeds another threshold.

[0043] In exemplary embodiments of the present disclosure, the condition is applied to terminal devices with quality of service, QoS, requirements.

[0044] A third aspect of the present disclosure provides an apparatus for a terminal device in a communication network. The apparatus for the terminal device may comprise: a processor; and a memory, the memory containing instructions executable by the processor. The apparatus for the terminal device is operative for: obtaining a first synchronization signal block measurement timing configuration, SMTC, before or after changing from a first cell to a second cell; adjusting an offset parameter in the first SMTC, based at least on a propagation delay in the second cell; and performing measurement in the second cell, based on the first SMTC with the adjusted offset parameter.

[0045] In exemplary embodiments of the present disclosure, the apparatus may be further operative to perform the method according to any of above embodiments.

[0046] A fourth aspect of the present disclosure provides an apparatus for a network node in a communication network. The apparatus for the network node may comprise: a processor; and a memory, the memory containing instructions executable by the processor. The apparatus for the network node is operative for: transmitting, a first synchronization signal block measurement timing configuration, SMTC, to a terminal device, before or after the terminal device changing from a first cell to a second cell; and indicating the terminal device whether to adjust an offset parameter in the first SMTC.

[0047] In exemplary embodiments of the present disclosure, the apparatus may be further operative to perform the method according to any of above embodiments.

[0048] A fifth aspect of the present disclosure provides computer-readable storage medium storing instructions, which when executed by at least one processor, cause the at least one processor to perform the method according to any of above embodiments.

[0049] Embodiments herein afford many advantages. According to embodiments of the present disclosure, a manner for enhancing SMTC for switching terminal device in communication network may be provided.

[0050] Particularly, the terminal device can apply STMC properly after being switched to and / or reselecting a cell with different SSB characteristics. The specific SSB measurement may be adjusted accordingly. Therefore, the influence of a moving base station / relay, such as a moving satellite, for the time align of SSB may be reduced. The measurement quality for the SSB in such situations may be enhanced.

[0051] BRIEF DESCRIPTION OF DRAWINGS

[0052] The above and other aspects, features, and benefits of various embodiments of the present disclosure will become more fully apparent, by way of example, from the following detailed description with reference to the accompanying drawings, in which like reference numerals or letters are used to designate like or equivalent elements. The drawings are illustrated for facilitating better understanding of the embodiments of the disclosure and not necessarily drawn to scale, in which:

[0053] FIG. 1 is a diagram showing an example architecture of a satellite network with bent pipe transponders.

[0054] FIG. 2 is a diagram showing an exemplary illustration of SSB, SMTC window, and measurement gap-

[0055] FIG. 3A is a flow chart showing a method performed by a terminal device, according to embodiments of the present disclosure.

[0056] FIG. 3B is a flow chart showing additional steps for the method in the FIG. 3 A.

[0057] FIG. 3C is a flow chart showing additional steps for the method in the FIG. 3 A.

[0058] FIG. 3D is a flow chart showing additional steps for the method in the FIG. 3 A.

[0059] FIG. 3E is a flow chart showing additional steps for the method in the FIG. 3 A.

[0060] FIG. 4A is a flow chart showing a method performed by a network node, according to embodiments of the present disclosure.

[0061] FIG. 4B is a flow chart showing additional steps for the method in the FIG. 4A.

[0062] FIG. 4C is a flow chart showing additional steps for the method in the FIG. 4A.

[0063] FIG. 4D is a flow chart showing additional steps for the method in the FIG. 4A.

[0064] FIG. 4E is a flow chart showing additional steps for the method in the FIG. 4A.

[0065] FIG. 5 is a block diagram showing an exemplary apparatus for a terminal device, which is suitable for perform the method according to embodiments of the disclosure.

[0066] FIG. 6 is a block diagram showing an exemplary apparatus for a network node, which is suitable for perform the method according to embodiments of the disclosure.

[0067] FIG. 7 is a block diagram showing an apparatus / computer readable storage medium, according to embodiments of the present disclosure.

[0068] FIG. 8 is a schematic showing units for the exemplary apparatus for a terminal device, according to embodiments of the present disclosure.

[0069] FIG. 9 is a block diagram showing an exemplary apparatus for a network node, which is suitable for perform the method according to embodiments of the disclosure.

[0070] FIG. 10 shows an example of a communication system 1000 in accordance with some embodiments.

[0071] FIG. 11 shows a UE 1100 in accordance with some embodiments.

[0072] FIG. 12 shows a network node 1200 in accordance with some embodiments.

[0073] FIG. 13 is a block diagram illustrating a virtualization environment 1300 in which functions implemented by some embodiments may be virtualized.

[0074] DETAILED DESCRIPTION

[0075] The embodiments of the present disclosure are described in detail with reference to the accompanying drawings. It should be understood that these embodiments are discussed only for the purpose of enabling those skilled persons in the art to better understand and thus implement the present disclosure, rather than suggesting any limitations on the scope of the present disclosure. Reference throughout this specification to features, advantages, or similar language does not imply that all of the features and advantages that may be realized with the present disclosure should be or are in any single embodiment of the disclosure. Rather, language referring to the features and advantages is understood to mean that a specific feature, advantage, or characteristic described in connection with an embodiment is included in at least one embodiment of the present disclosure. Furthermore, the described features, advantages, and characteristics of the disclosure may be combined in any suitable manner in one or more embodiments. One skilled in the relevant art will recognize that the disclosure may be practiced without one or more of the specific features or advantages of a particular embodiment. In other instances, additional features and advantages may be recognized in certain embodiments that may not be present in all embodiments of the disclosure.

[0076] Generally, all terms used herein are to be interpreted according to their ordinary meaning in the relevant technical field, unless a different meaning is clearly given and / or is implied from the context in which it is used. All references to a / an / the element, apparatus, component, means, step, etc. are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise. The steps of any methods disclosed herein do not have to be performed in the exact order disclosed, unless a step is explicitly described as following or preceding another step and / or where it is implicit that a step must follow or precede another step. Any feature of any of the embodiments disclosed herein may be applied to any other embodiment, wherever appropriate. Likewise, any advantage of any of the embodiments may apply to any other embodiments, and vice versa. Other objectives, features and advantages of the enclosed embodiments will be apparent from the following description.

[0077] As used herein, the term “network” or “communication network” refers to a network following any suitable wireless communication standards. For example, the wireless communication standards may comprise new radio (NR), long term evolution (LTE), LTE-Advanced, wideband code division multiple access (WCDMA), high-speed packet access (HSPA), Code Division Multiple Access (CDMA), Time Division Multiple Address (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency-Division Multiple Access (OFDMA), Single carrier frequency division multiple access (SC-FDMA) and other wireless networks. In the following description, the terms “network” and “system” can be used interchangeably. Furthermore, the communications between two devices in the network may be performed according to any suitable communication protocols, including, but not limited to, the wireless communication protocols as defined by a standard organization such as 3rd generation partnership project (3GPP) or the wired communication protocols.

[0078] The term “network node” used herein refers to a network device or network entity or network function or any other devices (physical or virtual) in a communication network. For example, the network node in the network may include a base station (BS), an access point (AP), a multi - cell / multicast coordination entity (MCE), a server node / function (such as a service capability server / application server, SCS / AS, group communication service application server, GCS AS, application function, AF), an exposure node / function (such as a service capability exposure function, SCEF, network exposure function, NEF), a unified data management, UDM, a home subscriber server, HSS, a session management function, SMF, an access and mobility management function, AMF, a mobility management entity, MME, a controller or any other suitable device in a wireless communication network. The BS may be, for example, a node B (NodeB or NB), an evolved NodeB (eNodeB or eNB), a next generation NodeB (gNodeB or gNB), a remote radio unit (RRU), a radio header (RH), a remote radio head (RRH), a relay, a low power node such as a femto, a pico, and so forth.

[0079] Yet further examples of the network node may comprise multi -standard radio (MSR) radio equipment such as MSR BSs, network controllers such as radio network controllers (RNCs) or base station controllers (BSCs), base transceiver stations (BTSs), transmission points, transmission nodes, positioning nodes and / or the like.

[0080] Further, the term “network node”, “network function”, “network entity” herein may also refer to any suitable node, function, entity which can be implemented (physically or virtually) in a communication network. For example, the 5G system (5GS) may comprise a plurality of NFs such as AMF (Access and mobility Function), SMF (Session Management Function), AUSF (Authentication Service Function), UDM (Unified Data Management), PCF (Policy Control Function), AF (Application Function), NEF (Network Exposure Function), UPF (User plane Function) and NRF (Network Repository Function), RAN (radio access network), SCP (service communication proxy), etc. In other embodiments, the network function may comprise different types of NFs (such as PCRF (Policy and Charging Rules Function), etc.) for example depending on the specific network.

[0081] The term “terminal device” refers to any end device that can access a communication network and receive services therefrom. By way of example and not limitation, the terminal device refers to a mobile terminal, user equipment (UE), or other suitable devices. The UE may be, for example, a Subscriber Station (SS), a Portable Subscriber Station, a Mobile Station (MS), or an Access Terminal (AT). The terminal device may include, but not limited to, a portable computer, an image capture terminal device such as a digital camera, a gaming terminal device, a music storage and a playback appliance, a mobile phone, a cellular phone, a smart phone, a voice over IP (VoIP) phone, a wireless local loop phone, a tablet, a wearable device, a personal digital assistant (PDA), a portable computer, a desktop computer, a wearable terminal device, a vehicle-mounted wireless terminal device, a wireless endpoint, a mobile station, a laptop-embedded equipment (LEE), a laptop-mounted equipment (LME), a USB dongle, a smart device, a wireless customer-premises equipment (CPE) and the like. In the following description, the terms “terminal device”, “terminal”, “user equipment” and “UE” may be used interchangeably. As one example, a terminal device may represent a UE configured for communication in accordance with one or more communication standards promulgated by the 3 GPP, such as 3GPP’ LTE standard or NR standard. As used herein, a “user equipment” or “UE” may not necessarily have a “user” in the sense of a human user who owns and / or operates the relevant device. In some embodiments, a terminal device may be configured to transmit and / or receive information without direct human interaction. For instance, a terminal device may be designed to transmit information to a network on a predetermined schedule, when triggered by an internal or external event, or in response to requests from the communication network. Instead, a UE may represent a device that is intended for sale to, or operation by, a human user but that may not initially be associated with a specific human user.

[0082] As yet another example, in an Internet of Things (loT) scenario, a terminal device may represent a machine or other device that performs monitoring and / or measurements, and transmits the results of such monitoring and / or measurements to another terminal device and / or network equipment. The terminal device may in this case be a machine-to-machine (M2M) device, which may in a 3GPP context be referred to as a machine-type communication (MTC) device. As one particular example, the terminal device may be a UE implementing the 3GPP narrow band internet of things (NB-IoT) standard. Particular examples of such machines or devices are sensors, metering devices such as power meters, industrial machinery, or home or personal appliances, for example refrigerators, televisions, personal wearables such as watches etc. In other scenarios, a terminal device may represent a vehicle or other equipment that is capable of monitoring and / or reporting on its operational status or other functions associated with its operation.

[0083] References in the specification to “one embodiment,” “an embodiment,” “an example embodiment,” and the like indicate that the embodiment described may include a particular feature, structure, or characteristic, but it is not necessary that every embodiment includes the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

[0084] It shall be understood that although the terms “first” and “second” etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and similarly, a second element could be termed a first element, without departing from the scope of example embodiments. As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed terms.

[0085] As used herein, the phrase “at least one of A and (or) B” should be understood to mean “only A, only B, or both A and B.” The phrase “A and / or B” should be understood to mean “only A, only B, or both A and B.” The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises”, “comprising”, “has”, “having”, “includes” and / or “including”, when used herein, specify the presence of stated features, elements, and / or components etc., but do not preclude the presence or addition of one or more other features, elements, components and / or combinations thereof.

[0086] It is noted that these terms as used in this document are used only for ease of description and differentiation among nodes, devices or networks etc. With the development of the technology, other terms with the similar / same meanings may also be used.

[0087] In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skills in the art to which this disclosure belongs.

[0088] As to Satellite Communications and Non-Terrestrial Networks (NTN), There is an ongoing resurgence of satellite communications. Several plans for satellite networks have been announced in the past few years. The target services vary, from backhaul and fixed wireless, to transportation, to outdoor mobile, to internet of things (loT). Satellite networks could complement mobile networks on the ground by providing connectivity to underserved areas and multicast / broadcast services. To benefit from the strong mobile ecosystem and economy of scale, adapting the terrestrial wireless access technologies including LTE and NR for satellite networks is drawing significant interest, which has been reflected in the 3rdgeneration partnership project (3GPP) standardization work. In 3GPP release 15, 3GPP started the work to prepare new radio (NR) for operation in a Non-Terrestrial Network (NTN). Here, the term NonTerrestrial Network - NTN - may refer to a NR NTN, i.e., an NTN that operates according to 3GPP NR technology adapted to satellite communication. The work was performed within the study item “NR to support Non-Terrestrial Networks” and resulted in 3GPP TR 38.811 V15.4.0, Study on New Radio (NR) to support Non-Terrestrial Networks. In 3GPP release 16, the work to prepare NR for operation in an NTN network continued with the study item “Solutions for NR to support Non-Terrestrial Network”, which has been captured in 3GPP TR 38.821 V16.2.0, Solutions for NR to support Non-Terrestrial Networks. In parallel the interest to adapt narrow band internet of things (NB-IoT) and Long Term Evolution- Machine Type Communication (LTE-M) for operation in NTN is growing. As a consequence, 3GPP release 17 contains both a work item on NR NTN (RP-193234, 3GPPTM Work Item Description, Solutions for NR to support non-terrestrial networks (NTN)) and a study item and work item on NB-IoT and LTE-M support for NTN (RP-193235, Study on NB-Iot / eMTC support for Non-Terrestrial Network and RP-211601, NB-IoT / eMTC support for Non-terrestrial Networks (NTN), RAN#92-e, Jun 2021, respectively). In the work on 3GPP release 18, a topic that is relevant to this disclosure is enhancements of NTN-NTN mobility, particularly random access channel-less (RACH-less) conditional handover.

[0089] FIG. 1 is a diagram showing an example architecture of a satellite network with bent pipe transponders.

[0090] FIG. 1 shows an example architecture of a satellite network with bent pipe transponders (i.e. the transparent payload architecture). The base station (BS) 1, such as a gNB, may be integrated in the gateway or connected to the gateway via a terrestrial connection (wire, optic fiber, wireless link).

[0091] A communication satellite 11 typically generates several beams over a given area. The footprint of a beam is usually in an elliptic shape, which has traditionally been considered as a cell, but cells consisting of the coverage footprint of multiple beams are not excluded in the 3GPP work. The footprint of a beam is also often referred to as a spotbeam. The footprint of a beam may move over the earth’s surface with the satellite movement or may be earth fixed with a beam pointing mechanism used by the satellite to compensate for the satellite’s motion (where the latter may be referred to as quasi-earth-fixed beams or quasi -earth-fixed cells). The size of a spotbeam depends on the system design, which may range from tens of kilometers to a few thousands of kilometers.

[0092] In a Low Earth Orbit (LEO) or Medium Earth Orbit (MEO) communication system, a large number of satellites deployed over a range of orbits are required to provide continuous coverage across the full globe. Launching a mega satellite constellation is both an expensive and time-consuming procedure. It is therefore expected that all LEO and MEO satellite constellations for some time will only provide partial earth-coverage. In case of some constellations dedicated to massive loT services with relaxed latency requirements, it may not even be necessary to support full earth-coverage. It may be sufficient to provide occasional or periodic coverage according to the orbital period of the constellation.

[0093] A 3GPP device 2 in RRC IDLE or RRC INACTIVE state is required to perform number of procedures including measurements for mobility purposes, paging monitoring, logging measurement results, tracking area update, and search for a new PLMN (public land mobile network), just to mention a few. These procedures will consume power in devices, and a general trend in 3 GPP has been to allow for relaxation of these procedures to prolong device battery life. This trend has been especially pronounced for loT devices supported by reduced capability (redcap), NB-IoT and LTE-M.

[0094] Propagation delay is an important aspect of satellite communications that is different from the delay expected in a terrestrial mobile system. For a bent pipe satellite network, the round-trip delay may, depending on the orbit height, range from tens of ms in the case of LEO satellites to several hundreds of ms for GEO satellites. As a comparison, the round-trip delays in terrestrial cellular networks are typically below 1 ms.

[0095] The distance between the UE 2 and a satellite 11 can vary significantly, depending on the position of the satellite and thus the elevation angle a seen by the UE. Assuming circular orbits, the minimum distance is realized when the satellite is directly above the UE (a = 90°), and the maximum distance when the satellite is at the smallest possible elevation angle. Table 1 shows the distances between satellite and UE for different orbital heights and elevation angles together with the one-way propagation delay and the maximum propagation delay difference (the difference from the propagation delay at a = 90°). Note that this table assumes regenerative payload architecture. For the transparent payload case, the propagation delay between gateway and satellite needs to be considered as well, unless the base station corrects for that.

[0096] The propagation delay may also be highly variable due to the high velocity of the LEO and MEO satellites and change in the order of 10 - 100 ps every second, depending on the orbit altitude and satellite velocity.

[0097] Such propagation delay will influence the transmission of signals between the satellite and a UE, such as a signal of SSB.

[0098] FIG. 2 is a diagram showing an exemplary illustration of SSB, SMTC window, and measurement gap-

[0099] NR synchronization signal (SS) consists of primary SS (PSS) and secondary SS (SSS). NR physical broadcast channel (PBCH) carries the very basic system information. The combination of SS and PBCH is referred to as SSB in NR. Multiple SSBs are transmitted in a localized burst set. Within an SS burst set, multiple SSBs can be transmitted in different beams. The transmission of SSBs within a localized burst set is confined to a 5 ms window. The set of possible SSB time locations within an SS burst set depends on the numerology which in most cases is uniquely identified by the frequency band. The SSB periodicity can be configured from the value set {5, 10, 20, 40, 80, 160} ms (where the unit used in the configuration is subframe, which has a duration of 1 ms).

[0100] A UE does not need to perform measurements with the same periodicity as the SSB periodicity. Accordingly, the SSB measurement time configuration (SMTC) has been introduced for NR. The signaling of SMTC window informs the UE of the timing and periodicity of SSBs that the UE can use for measurements. The SMTC window periodicity can be configured from the value set {5, 10, 20, 40, 80, 160} ms, matching the possible SSB periodicities. The SMTC window duration can be configured from the value set { 1, 2, 3, 4, 5} ms (where the unit used in the configuration is subframe, which has a duration of 1 ms). The UE may use the same RF module for measurements of neighboring cells and data transmission in the serving cell. Measurement gaps allow the UE to suspend the data transmission in the serving cell and perform the measurements of neighboring cells. The measurement gap repetition periodicity can be configured from the value set {20, 40, 80, 160} ms, the gap length can be configured from the value set { 1.5, 3, 3.5, 4, 5.5, 6, 10, 20} ms. Usually, the measurement gap length is configured to be larger than the SMTC window duration to allow for RF retuning time. Measurement gap time advance is also introduced to fine tune the relative position of the measurement gap with respect to the SMTC window. The measurement gap timing advance can be configured from the value set {0, 0.25, 0.5} ms.

[0101] The following can be considered as main challenges that need to be addressed in NTN: moving satellites (resulting in moving cells or switching cells), long propagation delays.

[0102] Moving satellites (resulting in moving or switching cells) causes new challenges since the default assumption in terrestrial network design, e.g., NR or LTE, is that cells are stationary. This is not the case in NTN, especially when LEO satellites are considered. A LEO satellite may be visible to a UE on the ground only for a few seconds or minutes. There are two different options for LEO deployment. The beam / cell coverage is fixed with respect to a geographical location with earth-fixed beams, i.e., steerable beams from satellites ensure that a certain beam covers the same geographical area even as the satellite moves in relation to the surface of the earth. On the other hand, with moving beams a LEO satellite has fixed antenna pointing direction in relation to the earth’s surface, e.g., perpendicular to the earth’s surface, and thus cell / beam coverage sweeps the earth as the satellite moves. In that case, the spotbeam, which is serving the UE, may switch every few seconds.

[0103] Long propagation delays cause new challenges since the propagation delays in terrestrial mobile systems are usually less than 1 millisecond. In contrast, the propagation delays in NTN can be much longer, ranging from several milliseconds (LEO) to hundreds of milliseconds (GEO) depending on the altitudes of the spaceborne or airborne platforms deployed in the NTN.

[0104] In terrestrial networks (TNs) the relative location in time of an SSB between a serving cell and a neighbor cell is fixed. The propagation delay within each cell depends on the cell size and UE location, and from UE’s perspective it will only vary due to UE movement.

[0105] On the contrary, in low-earth orbit (LEO) scenarios, even the propagation delay between UE and serving cell will vary over time, due to the movement of the satellite. Furthermore, the propagation delays towards neighbor cells on neighboring satellites will also change over time. The scenario will become worse when also accounting for feeder link delay and will increase with increasing satellite altitude.

[0106] Serving cell and target cell might not be necessarily time- and frame-synchronized when belonging to different satellites. The resulting time offset in SSB transmission between different cells needs to be considered as well for SMTC window and gap configuration towards the UE.

[0107] As exemplary characteristics, a satellite radio access network usually includes the following components:

[0108] • A satellite that refers to a space-borne platform. • An earth-based gateway that connects the satellite to a base station or a core network, depending on the choice of architecture.

[0109] • A feeder link that refers to the link between a gateway (GW) and a satellite.

[0110] • An access link, or service link, that refers to the link between a satellite and a user equipment (UE).

[0111] A communication satellite typically generates several beams over a given area. The footprint of a beam is usually in an elliptic shape, which has been traditionally considered as a cell (but a cell consisting of multiple beams is not precluded). The footprint of a beam is also often referred to as a spotbeam. Three types of beams or cells are supported in NTN:

[0112] • Earth-fixed beams / cells: provisioned by beam(s) continuously covering the same geographical areas all the time (e.g., in the case of Geostationary Earth Orbit (GEO) satellites).

[0113] • Quasi-Earth-fixed beams / cells: provisioned by beam(s) covering one geographic area for a limited period and a different geographic area during another period (e.g., in the case of Non- geostationary orbit (NGSO) satellites generating steerable beams).

[0114] • Earth-moving beams / cells: provisioned by beam(s) whose coverage area slides over the earth surface (e.g., in the case of NGSO satellites generating fixed or non-steerable beams).

[0115] Throughout this disclosure the terms beam and cell are used interchangeably, unless explicitly noted otherwise.

[0116] With Quasi-Earth-fixed beams / cells or earth-moving beams / cells, when the satellite serving the area is changed (which is referred to as satellite switch), all UEs connected in the old cell (i.e., UEs in RRC CONNECTED state) have to be handed over (or otherwise moved, e.g. using radio resource control (RRC) connection reestablishment) from the old to the new cell, and all UEs camping on the old cell (i.e., UEs in RRC IDLE or RRC INACTIVE state) have to perform cell reselection to the new cell. A consequence of a satellite switch is that both the service link (i.e., the link between the UE and the satellite) and the feeder link (i.e., the link between the satellite and the GW / gNB) are switched, and the serving cell is also switched.

[0117] A similar situation occurs in conjunction with feeder link switches, i.e., when the serving satellite remains the same, but its connection to the ground changes from one (old) GW / gNB to another (new) GW / gNB. Also, in this case there is switch between an old cell and a new cell (i.e., the old cell is replaced by a new cell).

[0118] Satellite switches and feeder link switches can both be referred to with the umbrella term “cell switch”.

[0119] There is NTN-specific information in the system information. Due to the special operating conditions in a Non-Terrestrial Network, the system information broadcasted in an NTN cell has to include NTN-specific information. To serve this purpose, a new system information block (SIB), SIB 19 is introduced in NR NTN which contains NTN-specific information. In loT NTN, the new SIB 31 more or less corresponds to SIB 19 in NR NTN.

[0120] For an RRC CONNECTED UE, when the UL synchronization timer (T430) expired, the UE shall perform the following:

[0121] • Inform lower layers that UL synchronization is lost; • Acquire SIB 19;

[0122] • Upon successful acquisition of SIB 19, restart T430 and inform lower layers when UL synchronization is obtained.

[0123] In 3GPP TS 38.3313GPP TS 38.331, V17.4.0, “Radio Resource Control (RRC) protocol specification (Release 17)” , SIB 19 is defined as follows in abstract syntax notation one (ASN.l) code:

[0124] - ASN1 START

[0125] - TAG-SIB 19-START

[0126] SIB19-rl7 ::= SEQUENCE { ntn-Config NTN-Config-rl7 OPTIONAL, - Need R t-Service-rl7 INTEGER (0..549755813887) OPTIONAL, - Need R referenceLocation-r 17 ReferenceLocation-r 17 OPTIONAL, - Need R ta-Report-rl7 ENUMERATED {enabled} OPTIONAL, - Need R lateNonCriticalExtension OCTET STRING OPTIONAL,

[0127] [[ ntn-NeighCellConfigListExt-vl720 NTN-NeighCellConfigList-rl7 OPTIONAL — Need R ]]

[0128] NTN-NeighCellConfigList-rl7 ::= SEQUENCE (SIZE(l..maxCellNTN-r 17)) OF NTN-

[0129] NeighCellConfig-r 17

[0130] NTN-NeighCellConfig-rl7 SEQUENCE { ntn-Config-rl7 NTN-Config-rl7 OPTIONAL, - Need R carrierFreq-rl7 ARFCN-ValueNR OPTIONAL, - Need R physCellId-rl7 PhysCellld OPTIONAL - Need R

[0131] }

[0132] - TAG-SIB 19-STOP

[0133] - ASN1STOP

[0134]

[0135] Satellite switch and feeder link switch with unchanged PCI is studied. In the work on 3GPP release 18, a topic that has been brought up and for which support has been agreed in RAN2 is that satellite switches and feeder link switches in quasi -Earth -fixed cells deployment (see above described) can be realized with unchanged carrier frequency and unchanged physical cell identity (PCI). It was firstly agreed that unchanged PCI can be supported with hard switch, i.e., where the pre-switch conditions and the post-switch conditions for the cell area coverage do not exist in parallel during a transition period, but instead the cell area’s coverage according to the post-switch conditions begins when the cell area’s coverage according to the pre-switch conditions end. The fact that the carrier frequency and PCI remains unchanged after the switch makes it look

[0136] (from the UE’s point of view) as the same cell, i.e., the UE will perceive it as the same cell before and after the switch (assuming that the carrier frequency and the PCI - at least locally - defines the cell). Because of this circumstance, it is questionable if this kind of switch should be referred to as a cell switch. Still, for convenience and simplification of the description, the switch will often be referred to as a cell switch, and the pre-switch conditions may be referred to as the old cell (or sometimes the source cell) and the post-switch conditions may be referred to as the new cell (or sometimes the target cell).

[0137] Regarding hard switch with unchanged PCI, RAN2 have made the following agreements:

[0138] • In quasi-earth fixed cell case, for hard satellite switch in the same Synchronization Signal Block (SSB) frequency and same gNB (no key change), satellite switching without PCI changing (not requiring layer 3 (L3) mobility) is supported, unless major technical issues are identified by RANI (RANI has replied that satellite switching without PCI changing (not requiring L3 mobility) is feasible from RANI perspective).

[0139] • An explicit indication (whether the switch is an unchanged PCI switch) will be introduced to enable the unchanged PCI switch.

[0140] • The unchanged PCI mechanism can be applied to the case where the coverage gap is zero or negligible (where there is no need to introduce t-gap (gap time) or t-Servicestart (new cell start time)). For further study (FFS) is whether it is needed to support scenarios that require the introduction of t-gap or t-start.

[0141] • PCI unchanged procedure can be performed without performing RACH.

[0142] • In the unchanged PCI case, the UE considers uplink (UL) synchronization timer expired at t-Service (current cell stop time) to stop any UL operation. FFS is on timeAlignmentTimer handling.

[0143] • In the unchanged PCI case, for RACH-based solution, the UE may trigger RACH immediately after DL synchronizing with the new satellite.

[0144] The benefit of the unchanged PCI mechanism is the reduced signaling overhead and switch interruption time.

[0145] Some companies argued that the unchanged PCI and carrier frequency principle can be used also for so-called soft switch, i.e. where the cell area is covered both according to pre-switch conditions and according to post-switch conditions (i.e. the old and the new serving satellite or the old and the new feeder links are used simultaneously, i.e. in parallel) during a transient coexistence period (also referred to as overlap period). In RAN2#123bis it was agreed that the unchanged PCI mechanism introduced for hard switch can also be applied to soft switch and there will be an indication (FFS is if explicit or implicit) whether hard switch or soft switch is used. To avoid interference between SSBs sent from the old and the new serving satellite, the SSBs sent from the old serving satellite must be different from those from the new serving satellite. This can be achieved by sending SSBs with different index or by sending time non-overlapped SSBs from the two satellites (i.e., SSBs sent from the new serving satellite is a time shifted version of SSBs sent from the old serving satellite). It is still under discussion which option should be adopted and how to provide target satellite SSB information to the UE.

[0146] As to SSB measurement timing configuration, NR has introduced cell signal measurement by using Synchronization Signal / Physical Broadcast Channel Block (SS / PBCH Block) (SSB), which is composed of the Synchronizations Signals (SS) (including Primary Synchronization Signal (PSS) and Secondary Synchronization Signal (SSS)) and the Physical Broadcast Channel (PBCH). The number of SSBs in one burst (SS burst) is a deployment configuration choice and may range between 1 and a maximum number, where the maximum number depends on the operating frequency. The SSB periodicity can be configured for each cell in the range of 5, 10, 20, 40, 80 or 160 ms. However, a mobile device does not need to measure cell signal with periodicity as the SSB and the appropriate measurement periodicity can be configured according to the channel condition. This is desirable and can help to avoid unnecessary measurements and reduce the power consumption on mobile devices.

[0147] In light of this, 3GPP introduced SS / PBCH Measurement Timing Configuration (also known as SSB Measurement Timing Configuration), abbreviated “SMTC”. The SMTC defines a periodic time window (SMTC window) in which SSB transmissions can be found. The SMTC consists of a window duration and a window periodicity and start offset for the window periodicity. The SMTC window periodicity can be longer than the SSB periodicity. The UE is only required to measure SSB within the SMTC window. For UE’s in RRC IDLE and RRC INACTIVE state, the SMTC(s) is(are) given in SIB2 for intra frequency neighbor cells and SIB4 for inter frequency neighbor cells. For UE’s in RRC CONNECTED state, the SMTC(s) is(are) provided in an RRCReconfiguration message.

[0148] The timing indicated in an SMTC, in particular the start offset of the SMTC window periodicity, is based on the timing of the PCell or serving cell.

[0149] In NTN, a measurement timing configuration list specific for NTN deployments is introduced (i.e., smtc4list in NR NTN). A UE measures NTN neighbor cells according to SMTC included in smtc4list. For smtc4list provided in SIB2 / SIB4, the offset of each SMTC in smtc4list is based on the assumption that the gNB-UE propagation delay difference between the serving cell and neighbour cells equals to 0 ms, and the UE can adjust the actual offset based on the actual propagation delay which it can derives based on its own location, the satellite location and the Common timing advance (TA) parameters and Kmac (Scheduling offset provided by network if downlink and uplink frame timing are not aligned at gNB) of the serving and neighbour cells. For smtc4list provided in RRCReconfiguration message, the offset is adjusted by the network (NW) and the UE shall use the SMTC with / without (w / o) adjusting the offset.

[0150] Short Message is used to indicate system information (SI) change and / or notify public warning system (PWS) (e.g., Earthquake and Tsunami Warning System (ETWS), Commercial Mobile Alert Service (CMAS)). It can be transmitted on physical downlink control channel (PDCCH) using downlink control information (DCI) format 1 0 scrambled with the paging- Radio Network Temporary Identifier (P-RNTI) with or without associated RRC Paging message. The Short Message has 8 bits, table 1 below gives the definition of each bit.

[0151] Table 2. Short Message content according to 3GPP TS 38.331 version 17.4.0.

[0152] If a UE receives a Short Message, the UE shall:

[0153] 1> if the UE is ETWS capable or CMAS capable, the etwsAndCmasIndication bit of Short Message is set, and the UE is provided with searchSpaceSIB 1 and searchSpaceOtherSystemlnformation on the active bandwidth part (BWP) or the initial BWP:

[0154] 2> immediately re-acquire the SI P

[0155] 2> if the UE is ETWS capable and si-Schedulinglnfo includes scheduling information for SIB6'.

[0156] 3> acquire SIB6 immediately;

[0157] 2> if the UE is ETWS capable and si-Schedulinglnfo includes scheduling information for SIB7'.

[0158] 3> acquire SIB7 immediately;

[0159] 2> if the UE is CMAS capable and si-Schedulinglnfo includes scheduling information for SIB8 '.

[0160] 3> acquire SIB8 immediately;

[0161] 1> if the UE is not configured with an eDRX cycle longer than the modification period and the systemlnfoModification bit of Short Message is set:

[0162] 2> re-acquire SIB1 from the start of the next modification period, determine from SIB1 which other SIB(s) are changed and re-acquire the SI message(s) carrying the changed SIB(s) from the start of the next modification period;

[0163] 1> if the UE is configured with an RRC IDLE eDRX cycle longer than the modification period and the systemlnfoModification-eDRX d. of Short Message is set:

[0164] 2> re-acquire SIB1 from the start of the next eDRX acquisition period boundary, determine from SIB1 which other SIB(s) are changed and re-acquire the SI message(s) carrying the changed SIB(s) from the start of the next eDRX acquisition period boundary. As an example, for soft switch with unchanged PCI, the SSBs sent from the old serving satellite must be different from those from the new serving satellite. This will lead to the following problems:

[0165] • SMTC specific for NTN neighbour cell measurements (i.e., SMTC in smtc4lisf) provided in RRCReconfiguration before the switch cannot be applied after the switch as the gNB-UE propagation delay difference between the serving cell and neighbour cells (very likely) changes when service link and / or feeder link switches in the serving cell so that the gNB-UE propagation delay in the serving cell (very likely) changes.

[0166] • All the SMTC provided in SIB2 / SIB4 and RRCReconfiguration and SMTC specific for TN neighbour cell measurements provided in RRCReconfiguration before the switch also cannot be applied after the switch if SSBs sent from the new serving satellite is a time shifted version of SSBs sent from the old serving satellite, which means the SSB timing in the serving cell is changed after the switch.

[0167] • The legacy UE cannot understand the target satellite SSB information thus cannot locate and synchronize to the SSB sent from the target satellite when executing (conditional) handover, which will lead to a (conditional) handover failure.

[0168] Therefore, it is necessary to study the above issues and develop corresponding solutions.

[0169] FIG. 3A is a flow chart showing a method performed by a terminal device, according to embodiments of the present disclosure.

[0170] As shown in FIG. 3A, a first aspect of the present disclosure provides a method 300 performed by a terminal device in a communication network. The method 300 comprises: a step S302, obtaining a first synchronization signal block measurement timing configuration, SMTC, before or after changing from a first cell to a second cell; a step S304, adjusting an offset parameter in the first SMTC, based at least on a propagation delay in the second cell; and a step S306, performing measurement in the second cell, based on the first SMTC with the adjusted offset parameter.

[0171] According to embodiments of the present disclosure, the terminal device can apply STMC properly after being switched to and / or reselecting a cell with different SSB characteristics. The specific SSB measurement may be adjusted accordingly. Therefore, the influence of a moving base station / relay, such as a moving satellite, for the time align of SSB may be reduced. The measurement quality for the SSB in such situations may be enhanced.

[0172] In exemplary embodiments of the present disclosure, a first synchronization signal block, SSB, is configured for the first cell, and a second SSB is configured for the second cell; and the first SSB and the second SSB occupy the same time position in schedule, or the first SSB and the second SSB have different SSB indices, or the second SSB is a time shifted version of the first SSB.

[0173] FIG. 3B is a flow chart showing additional steps for the method in the FIG. 3 A.

[0174] As shown in FIG. 3B, in exemplary embodiments of the present disclosure, the method 300 further comprises: a step S308, adjusting the offset parameter in the first SMTC, further based on a time offset in schedule between the first SSB and the second SSB.

[0175] In exemplary embodiments of the present disclosure, the offset parameter in the first SMTC is provided by the first cell or the second cell, based on the time offset in schedule between the first SSB and the second SSB.

[0176] According to embodiments of the present disclosure, when there is time offset in schedule between the first SSB and the second SSB, the network (first cell or second cell) may generate the offset parameter based on this time offset in schedule first, and then indicate the terminal device to further adjust the offset parameter based on propagation delay.

[0177] FIG. 3C is a flow chart showing additional steps for the method in the FIG. 3 A.

[0178] As shown in FIG. 3C, in exemplary embodiments of the present disclosure, the method 300 further comprises: a step S310, performing measurement in the second cell, based on the first SMTC without adjusting the offset parameter based on the propagation delay, in response to an indication from the first cell or the second cell.

[0179] According to embodiments of the present disclosure, the terminal device may also perform measurement without adjusting the offset parameter.

[0180] FIG. 3D is a flow chart showing additional steps for the method in the FIG. 3 A.

[0181] In exemplary embodiments of the present disclosure, the method 300 further comprises: a step S312, obtaining a second SMTC; and a step S314, performing measurement, based on the second SMTC.

[0182] FIG. 3E is a flow chart showing additional steps for the method in the FIG. 3 A.

[0183] In exemplary embodiments of the present disclosure, the method 300 further comprises: a step S316, transmitting a request for the first SMTC and / or the second SMTC.

[0184] In exemplary embodiments of the present disclosure, the first SMTC is obtained by the terminal device in a common control signaling; and the second SMTC is obtained by the terminal device in a dedicated signaling.

[0185] In exemplary embodiments of the present disclosure, the first SMTC is obtained by the terminal device in a system information block, SIB.

[0186] In exemplary embodiments of the present disclosure, the terminal device obtains the SIB regardless of whether an indication about a change in the SIB exists.

[0187] In exemplary embodiments of the present disclosure, the first SMTC is obtained by the terminal device in a dedicated signaling before the changing; and the second SMTC is obtained by the terminal device in a dedicated signaling after the changing.

[0188] In exemplary embodiments of the present disclosure, an indication from the first cell or the second cell indicates the terminal device at least one of: whether to adjust an offset parameter in the first SMTC based on a propagation delay in the second cell; using the first SMTC to perform measurement in the second cell; or using another SMTC to perform measurement in the second cell; and the indication is implicit or explicit.

[0189] In exemplary embodiments of the present disclosure, the terminal device is in a RRC CONNECTED state in the first cell and switches to the second cell; or the terminal device is in a RRC IDLE state or an INACTIVE state and reselects the second cell.

[0190] In exemplary embodiments of the present disclosure, terminal device changes from the first cell to the second cell without L3 mobility.

[0191] In exemplary embodiments of the present disclosure, the first cell and the second cell have the same physical cell identity.

[0192] In exemplary embodiments of the present disclosure, the first cell is provided by a first satellite and / or the second cell is provided by a second satellite.

[0193] Further, it should be noted the terminal device, and / or the network side (the first cell and / or the second cell) may also adjust an offset (such as a timing advance) of a measurement gap. Particularly, the UE may adjust the offset of the measurement based on a time shift (e.g., time offset in schedule) between the first SSB and the second SSB, and / or the propagation delay in the second cell. The network side may adjust / configure the offset of the measurement gap based on the time shift (e.g., time offset in schedule) between the first SSB and the second SSB. Such adjustments to offset of SMTC and to offset of measurement gap may be done separately, or simultaneously.

[0194] FIG. 4A is a flow chart showing a method performed by a network node, according to embodiments of the present disclosure.

[0195] As shown in FIG. 4A, a second aspect of the present disclosure provides a method 400 performed by a network node in a communication network. The method 400 comprises: a step S402, transmitting, a first synchronization signal block measurement timing configuration, SMTC, to a terminal device, before or after the terminal device changing from a first cell to a second cell; and a step S404, indicating the terminal device whether to adjust an offset parameter in the first SMTC.

[0196] In exemplary embodiments of the present disclosure, the network node indicates the terminal device whether to adjust the offset parameter in the first SMTC based on a propagation in the second cell; a first synchronization signal block, SSB, is configured for the first cell, and a second SSB is configured for the second cell; and the first SSB and the second SSB occupy the same time position in schedule, or the first SSB and the second SSB have different SSB indices, or the second SSB is a time shifted version of the first SSB.

[0197] FIG. 4B is a flow chart showing additional steps for the method in the FIG. 4A.

[0198] As show in FIG. 4B, in exemplary embodiments of the present disclosure, the method 400 further comprises: a step S406, providing the offset parameter in the first SMTC, based on the time offset in schedule between the first SSB and the second SSB.

[0199] FIG. 4C is a flow chart showing additional steps for the method in the FIG. 4A.

[0200] As show in FIG. 4C, in exemplary embodiments of the present disclosure, the method further comprises: a step S408, transmitting, to the terminal device, a second SMTC.

[0201] FIG. 4D is a flow chart showing additional steps for the method in the FIG. 4A.

[0202] As show in FIG. 4D, in exemplary embodiments of the present disclosure, the method further comprises: a step S410, receiving, from the terminal device, a request for the first SMTC and / or the second SMTC.

[0203] In exemplary embodiments of the present disclosure, the first SMTC is included in a common control signaling; wherein the second SMTC is included in a dedicated signaling.

[0204] In exemplary embodiments of the present disclosure, the first SMTC is included in a system information block, SIB.

[0205] In exemplary embodiments of the present disclosure, the terminal device obtains the SIB regardless of whether an indication about a change in the SIB exists. In exemplary embodiments of the present disclosure, the first SMTC is obtained by the terminal device in a dedicated signaling before the changing; and the second SMTC is obtained by the terminal device in a dedicated signaling after the changing.

[0206] In exemplary embodiments of the present disclosure, the terminal device is in a RRC CONNECTED state in the first cell and switches to the second cell; or the terminal device is in a RRC IDLE state or an INACTIVE state and reselects the second cell.

[0207] In exemplary embodiments of the present disclosure, terminal device changes from the first cell to the second cell without L3 mobility.

[0208] In exemplary embodiments of the present disclosure, the first cell and the second cell have the same physical cell identity.

[0209] In exemplary embodiments of the present disclosure, the first cell is provided by a first satellite and / or the second cell is provided by a second satellite; and the network node is a base station connected to the first satellite and / or the second satellite.

[0210] FIG. 4E is a flow chart showing additional steps for the method in the FIG. 4A.

[0211] As show in FIG. 4E, in exemplary embodiments of the present disclosure, the method 400 further comprises: S412, determining whether a condition related to served terminal devices is satisfied; and S414, when the condition is satisfied, performing at least one of the following actions: disabling the changing from the first cell to the second cell, when the second cell has the same PCI with the first cell; configuring a S SB in the first cell to use a different frequency than a S SB in the second cell; configuring the SSB in the second cell to be sent upon or after stopping the SSB in the first cell; or releasing terminal devices served by the network node and not supporting to obtain SSB information about the second cell.

[0212] In exemplary embodiments of the present disclosure, wherein the condition comprises at least one of: a number of RRC CONNECTED terminal devices served by the network node and not supporting to obtain SSB information about the second cell after the changing exceeds a threshold; and / or a ratio of RRC CONNECTED terminal devices served by the network node and not supporting to obtain SSB information about the second cell after the changing exceeds another threshold.

[0213] In exemplary embodiments of the present disclosure, the condition is applied to terminal devices with quality of service, QoS, requirements.

[0214] The exemplary embodiments elaborated in this disclosure propose mechanisms to properly apply SMTC after cell reselection and / or switch to a cell, in particular with unchanged PCI, and adapt the switch mechanism to alleviate that UEs not understanding the target satellite SSB information cannot perform cell switch properly.

[0215] The exemplary embodiments of the present disclosure provide some main aspects of the solutions, at least include the followings:

[0216] A UE applies SMTC(s) provided in common control signaling and adopting a self-determined offset based on propagation delay for cell measurements after switch with unchanged PCI until it is provided with dedicated SMTC(s).

[0217] A UE applies an earlier dedicated SMTC(s) provided before the switch, ignoring the configured offset and adopting a self-determined offset based on propagation delay for cell measurements after switch with unchanged PCI until it is provided with a new dedicated SMTC(s).

[0218] After switch to / reselecting a cell with unchanged PCI, a UE applies SMTC(s) acquired before the switch / reselection and adopting a self-determined offset based on the time offset between SSBs sent from the old satellite and SSBs from the new satellite.

[0219] SMTC(s) to be used after the switch to / reselecting a cell with unchanged PCI may be provided in SIB(s) which could be acquired by the UE before the switch / reselection and applied after the switch / reselection.

[0220] The gNB adapts the switch mechanism between hard switch with unchanged PCI, soft switch with unchanged PCI and switch with changed PCI depending on the number or the ratio of the served RRC CONNECTED UEs which do not understand the target satellite SSB information.

[0221] With the exemplary embodiments proposed in this disclosure a UE can apply STMC properly after switch to and / or reselecting a cell with unchanged PCI which enables proper neighbor cell measurements for both NTN neighbor cells and TN neighbor cells. Meanwhile, by adapting the switch mechanism UEs not understanding the target satellite SSB information can also perform cell switch properly.

[0222] The above description of the present disclosure provides some exemplary embodiments, but they are not limitation. The present disclosure may also provide following notes for implementing the solution of the present disclosure.

[0223] Note 1 : In this solution description, the term Non-Terrestrial Network (NTN) may, depending on the context, refer to either or both of NR NTN and loT NTN, but mostly the term may be used to refer to only NR NTN.

[0224] Note 2: The embodiments outlined below are described mainly in terms of NR based NTNs, but they are also equally applicable in an NTN based on LTE technology (and in particular loT NTN).

[0225] Note 3: The term “network” is used in the solution description to refer to a network node, which typically will be a radio access network (RAN) node, such as a gNB (e.g. in a NR based NTN) or an eNB (e.g. in an LTE based NTN, such as an loT NTN), but which may also be a base station or an access point in another type of network, or any other network node with the ability to directly or indirectly communicate with a UE. Refinements with finer granularity are also conceivable. For instance, a gNB may be an en-gNB, and if a split gNB architecture is applied (dividing the gNB into multiple separate entities or notes), the term “node” may refer to a part of the gNB, such as a gNB-CU (central unit) (often referred to as just CU), a gNB -DU (distributed unit) (often referred to as just DU), a gNB-CU-CP(control plane) or a gNB-CU-UP (user plane). Similarly, an eNB may be an ng-eNB, and if a split eNB architecture is applied (dividing the eNB into multiple separate entities or notes), the term “network” (and the network node it implies) may refer to a part of the eNB, such as an eNB- CU, an eNB-DU, an eNB-CU-CP or an eNB-CU-UP. Furthermore, the term “network” (and the network node it implies) may also refer to an IAB (Integrated access and backhaul)-donor, lAB-donor- CU, lAB-donor-DU, lAB-donor-CU-CP, or an lAB-donor-CU-UP.

[0226] Note 4: The terms “source node”, “target node” and “candidate target node” may sometimes be used in the solution description. The “node” in these terms should be understood as typically being a RAN node in an NTN based on NR technology, LTE technology or any other RAT in which handover, conditional handover or another mobility or conditional mobility concept is defined. In an NR based NTN, such a RAN node may be assumed to be a gNB. In an LTE based NTN (including an loT NTN), such a RAN node may be assumed to be an eNB. Alternatives to, or refinements of, these interpretations are however also conceivable. For instance, a gNB may be an en-gNB, and if a split gNB architecture is applied (dividing the gNB into multiple separate entities or notes), the term “node” may refer to a part of the gNB, such as a gNB-CU (often referred to as just CU), a gNB-DU (often referred to as just DU), a gNB-CU-CP or a gNB-CU-UP. Similarly, an eNB may be an ng-eNB, and if a split eNB architecture is applied (dividing the eNB into multiple separate entities or notes), the term “node” may refer to a part of the eNB, such as an eNB-CU, an eNB-DU, an eNB-CU-CP or an eNB-CU-UP. Furthermore, the “node” in the terms may also refer to an lAB-donor, lAB-donor-CU, lAB-donor-DU, lAB-donor-CU-CP, or an lAB-donor-CU-UP.

[0227] Note 5: The terms “Handover Command” and “HandoverCommand” are used interchangeably herein. Both terms refer to a UE configuration the target node (of a regular handover) or candidate target node (of a conditional handover), during the (conditional) handover preparation phase, compiles for the UE to be subject to the handover or conditional handover. This UE configuration is compiled in the form of an RRCReconfiguration message which is conveyed to the UE via the source node. The RRCReconfiguration is associated with a certain target cell or candidate target cell and the UE applies the RRCReconfiguration when / if it accesses the concerned (candidate) target cell controlled by the (candidate) target node. Formally, “HandoverCommand” is an RRC inter-node message which is conveyed from a target node or a candidate target node to a source node during the preparation of a handover or a conditional handover. It is carried by the HANDOVER REQUEST ACKNOWLEDGE XnAP in the Target NG-RAN node To Source NG-RAN node Transparent Container IE. The “HandoverCommand” RRC inter-node message contains an RRCReconfiguration the UE should apply when accessing the target cell or candidate target cell. The source node forwards this RRCReconfiguration (i.e., the HandoverCommand) to the UE. In this solution description, the term “HandoverCommand” is also used to denote this RRCReconfiguration when it is stored in a UE as a part of a conditional handover (CHO) configuration. This is also called the condRRCReconfig-rl6 IE in the CondReconfigToAddMod-rl6 IE (which contains the CHO configuration) in the CondReconfigToAddModList-rl6 IE in the ConditionalReconfiguration-rl6 IE. In the context of CHO, the terms “Conditional Handover Command”, “(Conditional) Handover Command” and “(conditional) Handover Command” may also be used.

[0228] Note 6: When CHO is configured for a UE, a cell which the UE potentially can connect to (i.e., if the CHO execution condition is fulfilled for the cell) is denoted as “candidate target cell”. Similarly, a RAN node controlling a candidate target cell is denoted as “candidate target node” or, in NR and NR NTN, “candidate target gNB”. However, once the UE has detected a fulfilled CHO execution condition for a candidate target cell, this terminology becomes a bit blurred. At this point, during the actual execution of the CHO and when the UE has connected to the new cell, the concerned cell may be referred to as either a “candidate target cell” or a “target cell”. Similarly, a RAN node controlling such a cell, may in this situation be referred to as either a “candidate target node” (or “candidate target gNB”) or a “target node” (or a “target gNB”). Note 7: A condition included in a CHO configuration governing the execution of the conditionally configured procedure may be referred to as a CHO execution condition, a HO execution condition, a CHO trigger condition, a HO trigger condition or sometimes just a trigger condition. Furthermore, phases of the procedure may be referred to as the Handover Preparation phase, the Handover Execution and / or the Handover Completion phase, or may be referred to as the Conditional Handover Preparation phase (or the (conditional) Handover Preparation phase), the Conditional Handover Execution phase and / or the Conditional Handover Completion phase.

[0229] Note 8: The target cell configuration (the RRCReconfiguration for the UE to use in the candidate target cell) and the CHO execution condition for each candidate target cell provided by the network to the UE may collectively be referred to as a CHO configuration, or, alternatively, each combination of candidate target cell, target cell configuration and CHO execution condition may be referred to as a CHO configuration (i.e., the terminology is not consistent).

[0230] Note 9: When writing message names of a communication protocol, two equivalent principles are used in this document. The writing principle “<protocol name> <message name> message”, for example “XnAP HANDOVER CANCEL message”, and the writing principle “<message name> <protocol name> message”, for example “HANDOVER CANCEL XnAP message” are equivalent, both referring to a message (i.e., “<message name>”) of a communication protocol (i.e., “<protocol name>”), e.g., the HANDOVER CANCEL message of the communication protocol XnAP. The same writing format equivalence applies to other communication protocols, such as NGAP.

[0231] Note 10: According to 3GPP agreements, as well as 3GPP TS 38.331 version 17.4.0, a time-based CHO execution condition will always be combined with a signal strength / quality CHO execution condition (both of which have to be fulfilled to trigger CHO execution). However, all the embodiments in the proposed solution which do not assume that the UE monitors a signal strength / quality condition (i.e., an A3, A4 or A5 event), are equally applicable if the UE is configured only with a time-based CHO execution condition. (Note that in embodiments describing lack of trigger of the CHO execution within the time window (i.e., between T1 and T2) assume that a signal strength / quality condition is configured but not fulfilled between T1 and T2).

[0232] Note 11 : The terms information element (IE) and field are used more or less interchangeably in this document. Also the term parameter is sometimes used to denote the same concept.

[0233] Note 12: Parameters / IEs / fields used in ASN.1 code as well as in procedural text in the 3GPP RRC specification for 5G / NR, i.e. 3GPP TS 38.331 version 17.4.0, are often named with a suffix indicating the number of the release of the 3 GPP standard the param eter / IE / field was introduced in (e.g. the suffix “-rl7” for a param eter / IE / field introduced in release 17 of the 3GPP standard). Parameters / IEs / fields following this naming convention are typically referred to both with and without the suffix, where the name including the suffix is used in the ASN.1 code (and thus defines the formal name from the ASN.1 compiler’s perspective), while the name without the suffix is used in running text, e.g., in field descriptions and procedural text. Relevant examples in the context of this document include the parameters / IEs / fields tl-Threshold-rl7 / tl-Threshold and t-Service-rl7 / t-Service. In this document, both name variants may occur for various parameters / IEs / fields.

[0234] Note 13: There are two main deployment principles for NTN: quasi-Earth-fixed cells and Earth- moving cells. These deployment principles are also referred to by other names. The quasi -Earth -fixed cells deployment principle is also referred to as quasi-Earth-fixed beams. The Earth-moving cells deployment principle is also referred to as Earth-moving beams, or shorter, moving or and moving beams.

[0235] Note 14: The terms “SSB set” and “SS burst” are used interchangeably herein.

[0236] Note 15: The fact that the carrier frequency and PCI remain unchanged after the switch makes it look (from the UE’s point of view) as the same cell, i.e., the UE will perceive it as the same cell before and after the switch (assuming that the carrier frequency and the PCI - at least locally - defines the cell). Because of this circumstance, it is questionable if this kind of switch should be referred to as a cell switch. Still, for convenience and simplification of the description, the switch will often be referred to as a cell switch. The term “cell” and “satellite” are used interchangeably herein.

[0237] Note 16: most embodiments are described with soft switch with unchanged PCI. However, the solutions are in general applied to the switch scenarios without L3 mobility and the SSBs sent from the old serving satellite are different from those sent from the new serving satellite. The first embodiment is applicable to both hard and soft switch with unchanged PCI.

[0238] Further, some detailed embodiments will be illustrated below.

[0239] In the first embodiment, after a switch with unchanged PCI, a (RRC CONNECTED) UE applies SMTC(s) provided in common control signaling for neighbour cell measurements and adjusts the actual offset based on the actual propagation delay (similar as it performs in RRC IDLE / INACTIVE) using the target satellite ephemeris and common TA parmeters, until it is provided with a dedicated SMTC(s) in a dedicated RRC signaling (i.e., in a RRCReconfiguration message). More specifically, the UE applies the SMTC provided in the relevant SIB(s) (SIB2 / SIB4) and adopts a self-determined offset based on propagation delay when it switches to the target cell. The SIB(s) (or the SI message(s) carrying the SIB(s)) may be acquired before or after the switch.

[0240] In another option, after a switch with unchanged PCI, a (RRC CONNECTED) UE applies an earlier dedicated SMTC(s) acquired before the switch for neighbour cell measurements until it is provided with a new dedicated SMTC(s) in a dedicated RRC signaling (i.e., in a RRCReconfiguration message), where the UE ignores the offset configured in the earlier STMC and adjusts the actual offset based on the actual propagation delay (similar as it performs in RRC IDLE / INACTIVE).

[0241] The above mechanism may only be adopted for NTN specific SMTC(s) for NTN neighbour cell measurements (i.e., SMTC(s) in smtc4list in NR NTN).

[0242] In a subembodiment, the gNB may indicate in a SIB (e.g., SIB19) or in dedicated RRC signaling (e.g., RRCReconfiguration message) whether a UE shall continue to use dedicated SMTC(s) with / without (w / o) ignoring the configured offset and adjusting the offset based on the actual propagation delay after the switch with unchanged PCI, where the dedicated SMTC(s) was acquired before the switch. This could be the case when e.g., the switch is a feeder link switch where the service link propagation delay does not change and the feeder link propagation delay via the old feeder link is similar to that via the new feeder link.

[0243] This embodiment works well when the SSBs sent from the old and the new satellite are differentiated by SSB index. In the second embodiment, when the SSBs sent from the old and the new satellite are differentiated by a shift in time, a (RRC CONNECTED) UE applies one or more of the followings for neighbour cell measurements after a soft switch with unchanged PCI until it is provided with SMTC(s) in a dedicated RRC signaling (i.e., in a RRCReconfiguration message):

[0244] The UE applies dedicated SMTC(s) acquired before the switch plus an offset when it switches to the target cell, where the offset is determined based on (e.g., equals to) the time offset between SSBs sent from the old satellite and SSBs from the new satellite.

[0245] The UE applies SMTC(s) provided in the relevant SIB(s) (SIB2 / SIB4) acquired before the switch plus an offset when it switches to the target cell, where the offset is determined based on (e.g., equals to) the time offset between SSBs sent from the old satellite and SSBs from the new satellite.

[0246] The gNB determines the SMTC(s) to be used after the switch (i.e., the offset is set based on (e.g., equals to) the time offset between SSBs sent from the old satellite and SSBs from the new satellite) and provides the SMTC(s) in SIB(s) (e.g., SIB 19 in NR NTN), where the SIB(s) (or the SI message carrying the SIB(s)) could be acquired by the UE before the switch, and the UE applies the acquired SMTC(s) after the switch w / o adjusting the offset based on the time offset between SSBs sent from the old satellite and SSBs from the new satellite (note that the UE may still adjust the offset based on the propagation delay). An indication may be added in the SIB(s) to indicate that the SMTC(s) are to be used after the switch, or it may be hardcoded in the specification that the SMTC(s) included in the SIB(s) are to be used after the switch.

[0247] The UE obtains the SMTC(s) by re-acquiring the relevant SIB(s) (e.g., SIB2 / SIB4) after the switch and then applies the SMTC(s) w / o adjusting the offset based on the time offset between SSBs sent from the old satellite and SSBs from the new satellite (note that the UE may still adjust the offset based on the propagation delay). The UE re-acquires the relevant SIB(s) (or the SI message(s) carrying the relevant SIB(s)) even it considers that the locally stored version of the relevant SIB(s) is still valid, e.g., even in case the received Short Message does not indicate a change in SIB (the systemlnfoModification bit or the systemlnfoModification-eDRX bit of the Short Message is not set) or the valueTag that are included in the si-Schedulinglnfo for the relevant SIB(s), where si- Schedulinglnfo is included in SIB1 received before or after the switch, is identical to valueTag associated with the stored version of the relevant SIB(s). One variant of this option is that which SIB(s) a (RRC CONNECTED) UE shall reacquire after soft switch with unchanged PCI (or simply a (RRC CONNECTED) UE shall reacquire SIB after soft switch with unchanged PCI) no matter the UE locally stored version of the SIB(s) is still valid or not may be hardcoded in the spec or configured by the NW via common or dedicated RRC signaling.

[0248] The gNB may indicate in a SIB (e.g., SIB 19) or in dedicated RRC signaling (e.g., RRCReconfiguration message) which of the above options the UE shall / could apply, different options may be applied for SMTC(s) used for TN neighbour cell measurements and SMTC(s) used for NTN neighbour cell measurements.

[0249] In a variant of the previous embodiment, upon the cell switch, the UE discards all measurement and reporting configuration related to NTN neighbour cells for which it does not have updated neighbour cell satellite assistance information (e.g., ntn-Config). For example, network may configure neighbour measurements for cells provided by satellites which are not included in the neighbour cell list of SIB 19 (NTN-NeighCellConfigList-rl7). In this case, the UE can only do an autonomous adjustment of SMTCs upon the switch for those cells provided by satellites, whose assistance information is present in SIB 19.

[0250] In the third embodiment, when the SSBs sent from the old and the new satellite are differentiated by a shift in time, a RRC IDLE / INACTIVE UE applies one or more of the followings for neighbour cell measurements after reselecting a cell with unchanged PCI:

[0251] The UE applies SMTC(s) provided in the relevant SIB(s) (SIB2 / SIB4) acquired before the reselection plus an offset after the reselection, where the offset is determined based on (e.g., equals to) the time offset between SSBs sent from the old satellite and SSBs from the new satellite.

[0252] The gNB determines the SMTC(s) to be used after the reselection (i.e., the offset is set based on (e.g., equals to) the time offset between SSBs sent from the old satellite and SSBs from the new satellite) and provides the SMTC(s) in SIB(s) (e.g., SIB19 in NR NTN), where the SIB(s) (or the SI message carrying the SIB(s)) could be acquired by the UE before the reselection, and the UE applies the acquired SMTC(s) after the reselection w / o adjusting the offset based on the time offset between SSBs sent from the old satellite and SSBs from the new satellite (note that the UE may still adjust the offset based on the propagation delay). An indication may be added in the SIB(s) to indicate that the SMTC(s) are to be used after the reselection, or it may be hardcoded in the specification that the SMTC(s) included in the SIB(s) are to be used after the reselection.

[0253] The UE obtains the SMTC(s) by re-acquiring the relevant SIB(s) (e.g., SIB2 / SIB4) after the reselection and then applies the SMTC(s) w / o adjusting the offset based on the time offset between SSBs sent from the old satellite and SSBs from the new satellite (note that the UE may still adjust the offset based on the propagation delay). The UE re-acquires the relevant SIB(s) (or the SI message(s) carrying the relevant SIB(s)) even it considers that the locally stored version of the relevant SIB(s) is still valid, e.g., even in case the received Short Message does not indicate a change in SIB (the systemlnfoModification bit or the systemlnfoModification-eDRX bit of the Short Message is not set) or the valueTag that are included in the si-Schedulinglnfo for the relevant SIB(s), where si- Schedulinglnfo is included in SIB1 received before or after the reselection, is identical to valueTag associated with the stored version of the relevant SIB(s). One variant of this option is that which SIB(s) a RRC IDLE / INACTIVE UE shall reacquire after reselecting a cell with unchanged PCI (or simply a RRC IDLE / INACTIVE UE shall reacquire SIB after reselecting a cell with unchanged PCI) no matter the UE locally stored version of the SIB(s) is still valid or not may be hardcoded in the spec or configured by the NW via common signaling.

[0254] In the fourth embodiment, a UE can request the gNB to provide an updated measurement and reporting configuration after the switch. This request can be carried out with the use of Random Access (e.g., CFRA), or with an MAC CE, SR, or RRC message.

[0255] In the fifth embodiment, in case the number of legacy RRC CONNECTED UEs served by a gNB and not understanding the target satellite SSB information exceeds a certain threshold and / or the ratio of legacy RRC CONNECTED UEs served by the gNB and not understanding the target satellite SSB information exceeds another certain threshold, the gNB performs one or more of the following actions such that the target satellite SSB information is not required for performing the switch and the UEs not understanding the target satellite SSB information can perform the switch properly (Note that the gNB is aware of which UEs in the cell support the unchanged PCI feature from their UE Radio Access capability information):

[0256] Disables the unchanged PCI switch mechanism.

[0257] The SSBs sent from the old satellite are put in a different frequency than the SSBs sent from the new satellite.

[0258] Still adopts the unchanged PCI switch mechanism and the same SSBs are sent from the old satellite and the new satellite, meanwhile the SSBs are sent from the new satellite upon or after stopping sending the SSBs from the old satellite (i.e., a hard switch with unchanged PCI is adopted even though the new satellite can start to serve the area before the old satellite leaves the area).

[0259] Still adopts the unchanged PCI switch mechanism and releases all UEs which do not understand the target satellite SSB information.

[0260] This means the gNB adapting the switch mechanism between e.g., hard switch with unchanged PCI, soft switch with unchanged PCI and switch with changed PCI depending on the number or the ratio of the served RRC CONNECTED UEs which do not understand the target satellite SSB information.

[0261] In a sub-embodiment, when counting the number or the ratio of the served RRC CONNECTED UEs which do not understand the target satellite SSB information, the QoS aspects may be taken into account, e.g., the gNB may only consider the UEs configured with radio bearer(s) / logical channel(s) associated with priority higher than a threshold and / or the required latency lower than another threshold.

[0262] FIG. 5 is a block diagram showing an exemplary apparatus for a terminal device, which is suitable for perform the method according to embodiments of the disclosure.

[0263] As shown in FIG. 5, an apparatus 50 for a terminal device in a communication network, may comprise: a processor 501; and a memory 502. The memory contains instructions executable by the processor. The apparatus 60 for the terminal device is operative for: obtaining a first synchronization signal block measurement timing configuration, SMTC, before or after changing from a first cell to a second cell; adjusting an offset parameter in the first SMTC, based at least on a propagation delay in the second cell; and performing measurement in the second cell, based on the first SMTC with the adjusted offset parameter.

[0264] In embodiments of the present disclosure, the apparatus 60 is further operative to perform the method according to any of the above embodiments, such as these shown in FIG. 3 A-3E.

[0265] FIG. 6 is a block diagram showing an exemplary apparatus for a network node, which is suitable for perform the method according to embodiments of the disclosure.

[0266] As shown in FIG. 6, an apparatus 60 for a network node may comprise: a processor 601; and a memory 602. The memory contains instructions executable by the processor. The apparatus 70 for the wireless device is operative for: transmitting, a first synchronization signal block measurement timing configuration, SMTC, to a terminal device, before or after the terminal device changing from a first cell to a second cell; and indicating the terminal device whether to adjust an offset parameter in the first SMTC.

[0267] In embodiments of the present disclosure, the apparatus 60 may be further operative to perform the method according to any of above embodiments, such as these shown in FIG. 4A-4E.

[0268] The processors 501, 601 may be any kind of processing component, such as one or more microprocessor or microcontrollers, as well as other digital hardware, which may include digital signal processors (DSPs), special-purpose digital logic, and the like. The memories 502, 602 may be any kind of storage component, such as read-only memory (ROM), random-access memory, cache memory, flash memory devices, optical storage devices, etc.

[0269] FIG. 7 is a block diagram showing an apparatus / computer readable storage medium, according to embodiments of the present disclosure.

[0270] As shown in FIG. 7, the computer-readable storage medium 70, or any other kind of product, storing instructions 701 which when executed by at least one processor, cause the at least one processor to perform the method according to any one of the above embodiments, such as these shown in FIG. 3A-3E, 4A-4E.

[0271] In addition, the present disclosure may also provide a carrier containing the computer program / instructions as mentioned above, wherein the carrier is one of an electronic signal, optical signal, radio signal, or computer readable storage medium. The computer readable storage medium can be, for example, an optical compact disk or an electronic memory device like a RAM (random access memory), a ROM (read only memory), Flash memory, magnetic tape, CD-ROM, DVD, Blueray disc and the like.

[0272] FIG. 8 is a schematic showing units for the exemplary apparatus for a terminal device, according to embodiments of the present disclosure.

[0273] As shown in FIG. 8, the apparatus 80 for a terminal device may comprise: an obtaining unit 802, configured for obtaining a first synchronization signal block measurement timing configuration, SMTC, before or after changing from a first cell to a second cell; an adjusting unit 804, configured for adjusting an offset parameter in the first SMTC, based at least on a propagation delay in the second cell; and a performing unit 806, configured for performing measurement in the second cell, based on the first SMTC with the adjusted offset parameter.

[0274] In embodiments of the present disclosure, the apparatus 80 is further operative to perform the method according to any of the above embodiments, such as these shown in FIG. 3 A-3E.

[0275] FIG. 9 is a block diagram showing an exemplary apparatus for a network node, which is suitable for perform the method according to embodiments of the disclosure.

[0276] As shown in FIG. 9, an apparatus 90 for a network node in a communication network may comprise: a transmitting unit 902, configured for transmitting, a first synchronization signal block measurement timing configuration, SMTC, to a terminal device, before or after the terminal device changing from a first cell to a second cell; and an indicating unit 904, configured for indicating the terminal device whether to adjust an offset parameter in the first SMTC.

[0277] In embodiments of the present disclosure, the apparatus 90 may be further operative to perform the method according to any of above embodiments, such as these shown in FIG. 4A-4E.

[0278] The term ‘unit’ may have conventional meaning in the field of electronics, electrical devices and / or electronic devices and may include, for example, electrical and / or electronic circuitry, devices, modules, processors, memories, logic solid state and / or discrete devices, computer programs or instructions for carrying out respective tasks, procedures, computations, outputs, and / or displaying functions, and so on, as such as those that are described herein.

[0279] With these units, the apparatus may not need a fixed processor or memory, any computing resource and storage resource may be arranged from at least one network node / device / entity / apparatus relating to the communication system. The virtualization technology and network computing technology (e.g., cloud computing) may be further introduced, so as to improve the usage efficiency of the network resources and the flexibility of the network.

[0280] The techniques described herein may be implemented by various means so that an apparatus implementing one or more functions of a corresponding apparatus described with an embodiment comprises not only prior art means, but also means for implementing the one or more functions of the corresponding apparatus described with the embodiment and it may comprise separate means for each separate function, or means that may be configured to perform two or more functions. For example, these techniques may be implemented in hardware (one or more apparatuses), firmware (one or more apparatuses), software (one or more modules), or combinations thereof. For a firmware or software, implementation may be made through modules (e.g., procedures, functions, and so on) that perform the functions described herein.

[0281] Particularly, these function units may be implemented either as a network element on a dedicated hardware, as a software instance running on a dedicated hardware, or as a virtualized function instantiated on an appropriate platform, e.g., on a cloud infrastructure.

[0282] FIG. 10 shows an example of a communication system 1000 in accordance with some embodiments.

[0283] In the example, the communication system 1000 includes a telecommunication network 1002 that includes an access network 1004, such as a radio access network (RAN), and a core network 1006, which includes one or more core network nodes 1008. The access network 1004 includes one or more access network nodes, such as network nodes 1010a and 1010b (one or more of which may be generally referred to as network nodes 1010), or any other similar 3rdGeneration Partnership Project (3 GPP) access node or non-3GPP access point. The network nodes 1010 facilitate direct or indirect connection of user equipment (UE), such as by connecting UEs 1012a, 1012b, 1012c, and 1012d (one or more of which may be generally referred to as UEs 1012) to the core network 1006 over one or more wireless connections.

[0284] Example wireless communications over a wireless connection include transmitting and / or receiving wireless signals using electromagnetic waves, radio waves, infrared waves, and / or other types of signals suitable for conveying information without the use of wires, cables, or other material conductors. Moreover, in different embodiments, the communication system 1000 may include any number of wired or wireless networks, network nodes, UEs, and / or any other components or systems that may facilitate or participate in the communication of data and / or signals whether via wired or wireless connections. The communication system 1000 may include and / or interface with any type of communication, telecommunication, data, cellular, radio network, and / or other similar type of system. The UEs 1012 may be any of a wide variety of communication devices, including wireless devices arranged, configured, and / or operable to communicate wirelessly with the network nodes 1010 and other communication devices. Similarly, the network nodes 1010 are arranged, capable, configured, and / or operable to communicate directly or indirectly with the UEs 1012 and / or with other network nodes or equipment in the telecommunication network 1002 to enable and / or provide network access, such as wireless network access, and / or to perform other functions, such as administration in the telecommunication network 1002.

[0285] In the depicted example, the core network 1006 connects the network nodes 1010 to one or more hosts, such as host 1016. These connections may be direct or indirect via one or more intermediary networks or devices. In other examples, network nodes may be directly coupled to hosts. The core network 1006 includes one more core network nodes (e.g., core network node 1008) that are structured with hardware and software components. Features of these components may be substantially similar to those described with respect to the UEs, network nodes, and / or hosts, such that the descriptions thereof are generally applicable to the corresponding components of the core network node 1008. Example core network nodes include functions of one or more of a Mobile Switching Center (MSC), Mobility Management Entity (MME), Home Subscriber Server (HSS), Access and Mobility Management Function (AMF), Session Management Function (SMF), Authentication Server Function (AUSF), Subscription Identifier De-concealing function (SIDF), Unified Data Management (UDM), Security Edge Protection Proxy (SEPP), Network Exposure Function (NEF), and / or a User Plane Function (UPF).

[0286] The host 1016 may be under the ownership or control of a service provider other than an operator or provider of the access network 1004 and / or the telecommunication network 1002, and may be operated by the service provider or on behalf of the service provider. The host 1016 may host a variety of applications to provide one or more service. Examples of such applications include live and prerecorded audio / video content, data collection services such as retrieving and compiling data on various ambient conditions detected by a plurality of UEs, analytics functionality, social media, functions for controlling or otherwise interacting with remote devices, functions for an alarm and surveillance center, or any other such function performed by a server.

[0287] As a whole, the communication system 1000 of FIG. 10 enables connectivity between the UEs, network nodes, and hosts. In that sense, the communication system may be configured to operate according to predefined rules or procedures, such as specific standards that include, but are not limited to: Global System for Mobile Communications (GSM); Universal Mobile Telecommunications System (UMTS); Long Term Evolution (LTE), and / or other suitable 2G, 3G, 4G, 5G standards, or any applicable future generation standard (e.g., 6G); wireless local area network (WLAN) standards, such as the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standards (WiFi); and / or any other appropriate wireless communication standard, such as the Worldwide Interoperability for Microwave Access (WiMax), Bluetooth, Z-Wave, Near Field Communication (NFC) ZigBee, LiFi, and / or any low-power wide-area network (LPWAN) standards such as LoRa and Sigfox.

[0288] In some examples, the telecommunication network 1002 is a cellular network that implements 3 GPP standardized features. Accordingly, the telecommunications network 1002 may support network slicing to provide different logical networks to different devices that are connected to the telecommunication network 1002. For example, the telecommunications network 1002 may provide Ultra Reliable Low Latency Communication (URLLC) services to some UEs, while providing Enhanced Mobile Broadband (eMBB) services to other UEs, and / or Massive Machine Type Communication (mMTC) / Massive loT services to yet further UEs.

[0289] In some examples, the UEs 1012 are configured to transmit and / or receive information without direct human interaction. For instance, a UE may be designed to transmit information to the access network 1004 on a predetermined schedule, when triggered by an internal or external event, or in response to requests from the access network 1004. Additionally, a UE may be configured for operating in single- or multi-RAT or multi -standard mode. For example, a UE may operate with any one or combination of Wi-Fi, NR (New Radio) and LTE, i.e. being configured for multi-radio dual connectivity (MR-DC), such as E-UTRAN (Evolved-UMTS Terrestrial Radio Access Network) New Radio - Dual Connectivity (EN-DC).

[0290] In the example, the hub 1014 communicates with the access network 1004 to facilitate indirect communication between one or more UEs (e.g., UE 1012c and / or 1012d) and network nodes (e.g., network node 1010b). In some examples, the hub 1014 may be a controller, router, content source and analytics, or any of the other communication devices described herein regarding UEs. For example, the hub 1014 may be a broadband router enabling access to the core network 1006 for the UEs. As another example, the hub 1014 may be a controller that sends commands or instructions to one or more actuators in the UEs. Commands or instructions may be received from the UEs, network nodes 1010, or by executable code, script, process, or other instructions in the hub 1014. As another example, the hub 1014 may be a data collector that acts as temporary storage for UE data and, in some embodiments, may perform analysis or other processing of the data. As another example, the hub 1014 may be a content source. For example, for a UE that is a VR headset, display, loudspeaker or other media delivery device, the hub 1014 may retrieve VR assets, video, audio, or other media or data related to sensory information via a network node, which the hub 1014 then provides to the UE either directly, after performing local processing, and / or after adding additional local content. In still another example, the hub 1014 acts as a proxy server or orchestrator for the UEs, in particular in if one or more of the UEs are low energy loT devices.

[0291] The hub 1014 may have a constant / persistent or intermittent connection to the network node 1010b. The hub 1014 may also allow for a different communication scheme and / or schedule between the hub 1014 and UEs (e.g., UE 1012c and / or 1012d), and between the hub 1014 and the core network 1006. In other examples, the hub 1014 is connected to the core network 1006 and / or one or more UEs via a wired connection. Moreover, the hub 1014 may be configured to connect to an M2M service provider over the access network 1004 and / or to another UE over a direct connection. In some scenarios, UEs may establish a wireless connection with the network nodes 1010 while still connected via the hub 1014 via a wired or wireless connection. In some embodiments, the hub 1014 may be a dedicated hub - that is, a hub whose primary function is to route communications to / from the UEs from / to the network node 1010b. In other embodiments, the hub 1014 may be a non-dedicated hub - that is, a device which is capable of operating to route communications between the UEs and network node 1010b, but which is additionally capable of operating as a communication start and / or end point for certain data channels.

[0292] FIG. 11 shows a UE 1100 in accordance with some embodiments. As used herein, a UE refers to a device capable, configured, arranged and / or operable to communicate wirelessly with network nodes and / or other UEs. Examples of a UE include, but are not limited to, a smart phone, mobile phone, cell phone, voice over IP (VoIP) phone, wireless local loop phone, desktop computer, personal digital assistant (PDA), wireless cameras, gaming console or device, music storage device, playback appliance, wearable terminal device, wireless endpoint, mobile station, tablet, laptop, laptop- embedded equipment (LEE), laptop-mounted equipment (LME), smart device, wireless customerpremise equipment (CPE), vehicle-mounted or vehicle embedded / integrated wireless device, etc. Other examples include any UE identified by the 3rd Generation Partnership Project (3 GPP), including a narrow band internet of things (NB-IoT) UE, a machine type communication (MTC) UE, and / or an enhanced MTC (eMTC) UE.

[0293] A UE may support device-to-device (D2D) communication, for example by implementing a 3GPP standard for sidelink communication, Dedicated Short-Range Communication (DSRC), vehicle- to-vehicle (V2V), vehicle-to-infrastructure (V2I), or vehicle-to-everything (V2X). In other examples, a UE may not necessarily have a user in the sense of a human user who owns and / or operates the relevant device. Instead, a UE may represent a device that is intended for sale to, or operation by, a human user but which may not, or which may not initially, be associated with a specific human user (e.g., a smart sprinkler controller). Alternatively, a UE may represent a device that is not intended for sale to, or operation by, an end user but which may be associated with or operated for the benefit of a user (e.g., a smart power meter).

[0294] The UE 1100 includes processing circuitry 1102 that is operatively coupled via a bus 1104 to an input / output interface 1106, a power source 1108, a memory 1110, a communication interface 1112, and / or any other component, or any combination thereof. Certain UEs may utilize all or a subset of the components shown in FIG. 11. The level of integration between the components may vary from one UE to another UE. Further, certain UEs may contain multiple instances of a component, such as multiple processors, memories, transceivers, transmitters, receivers, etc.

[0295] The processing circuitry 1102 is configured to process instructions and data and may be configured to implement any sequential state machine operative to execute instructions stored as machine-readable computer programs in the memory 1110. The processing circuitry 1102 may be implemented as one or more hardware-implemented state machines (e.g., in discrete logic, field- programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), etc.); programmable logic together with appropriate firmware; one or more stored computer programs, general -purpose processors, such as a microprocessor or digital signal processor (DSP), together with appropriate software; or any combination of the above. For example, the processing circuitry 1102 may include multiple central processing units (CPUs).

[0296] In the example, the input / output interface 1106 may be configured to provide an interface or interfaces to an input device, output device, or one or more input and / or output devices. Examples of an output device include a speaker, a sound card, a video card, a display, a monitor, a printer, an actuator, an emitter, a smartcard, another output device, or any combination thereof. An input device may allow a user to capture information into the UE 1100. Examples of an input device include a touch-sensitive or presence-sensitive display, a camera (e.g., a digital camera, a digital video camera, a web camera, etc.), a microphone, a sensor, a mouse, a trackball, a directional pad, a trackpad, a scroll wheel, a smartcard, and the like. The presence-sensitive display may include a capacitive or resistive touch sensor to sense input from a user. A sensor may be, for instance, an accelerometer, a gyroscope, a tilt sensor, a force sensor, a magnetometer, an optical sensor, a proximity sensor, a biometric sensor, etc., or any combination thereof. An output device may use the same type of interface port as an input device. For example, a Universal Serial Bus (USB) port may be used to provide an input device and an output device.

[0297] In some embodiments, the power source 1108 is structured as a battery or battery pack. Other types of power sources, such as an external power source (e.g., an electricity outlet), photovoltaic device, or power cell, may be used. The power source 1108 may further include power circuitry for delivering power from the power source 1108 itself, and / or an external power source, to the various parts of the UE 1100 via input circuitry or an interface such as an electrical power cable. Delivering power may be, for example, for charging of the power source 1108. Power circuitry may perform any formatting, converting, or other modification to the power from the power source 1108 to make the power suitable for the respective components of the UE 1100 to which power is supplied.

[0298] The memory 1110 may be or be configured to include memory such as random access memory (RAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), magnetic disks, optical disks, hard disks, removable cartridges, flash drives, and so forth. In one example, the memory 1110 includes one or more application programs 1114, such as an operating system, web browser application, a widget, gadget engine, or other application, and corresponding data 1116. The memory 1110 may store, for use by the UE 1100, any of a variety of various operating systems or combinations of operating systems.

[0299] The memory 1110 may be configured to include a number of physical drive units, such as redundant array of independent disks (RAID), flash memory, USB flash drive, external hard disk drive, thumb drive, pen drive, key drive, high-density digital versatile disc (HD-DVD) optical disc drive, internal hard disk drive, Blu-Ray optical disc drive, holographic digital data storage (HDDS) optical disc drive, external mini -dual in-line memory module (DIMM), synchronous dynamic random access memory (SDRAM), external micro-DIMM SDRAM, smartcard memory such as tamper resistant module in the form of a universal integrated circuit card (UICC) including one or more subscriber identity modules (SIMs), such as a USIM and / or ISIM, other memory, or any combination thereof. The UICC may for example be an embedded UICC (eUICC), integrated UICC (iUICC) or a removable UICC commonly known as ‘SIM card.’ The memory 1110 may allow the UE 1100 to access instructions, application programs and the like, stored on transitory or non-transitory memory media, to off-load data, or to upload data. An article of manufacture, such as one utilizing a communication system may be tangibly embodied as or in the memory 1110, which may be or comprise a device- readable storage medium. The processing circuitry 1102 may be configured to communicate with an access network or other network using the communication interface 1112. The communication interface 1112 may comprise one or more communication subsystems and may include or be communicatively coupled to an antenna 1122. The communication interface 1112 may include one or more transceivers used to communicate, such as by communicating with one or more remote transceivers of another device capable of wireless communication (e.g., another UE or a network node in an access network). Each transceiver may include a transmitter 1118 and / or a receiver 1120 appropriate to provide network communications (e.g., optical, electrical, frequency allocations, and so forth). Moreover, the transmitter 1118 and receiver 1120 may be coupled to one or more antennas (e.g., antenna 1122) and may share circuit components, software or firmware, or alternatively be implemented separately.

[0300] In the illustrated embodiment, communication functions of the communication interface 1112 may include cellular communication, Wi-Fi communication, LPWAN communication, data communication, voice communication, multimedia communication, short-range communications such as Bluetooth, near-field communication, location-based communication such as the use of the global positioning system (GPS) to determine a location, another like communication function, or any combination thereof. Communications may be implemented in according to one or more communication protocols and / or standards, such as IEEE 802.11, Code Division Multiplexing Access (CDMA), Wideband Code Division Multiple Access (WCDMA), GSM, LTE, New Radio (NR), UMTS, WiMax, Ethernet, transmission control protocol / intemet protocol (TCP / IP), synchronous optical networking (SONET), Asynchronous Transfer Mode (ATM), QUIC, Hypertext Transfer Protocol (HTTP), and so forth.

[0301] Regardless of the type of sensor, a UE may provide an output of data captured by its sensors, through its communication interface 1112, via a wireless connection to a network node. Data captured by sensors of a UE can be communicated through a wireless connection to a network node via another UE. The output may be periodic (e.g., once every 15 minutes if it reports the sensed temperature), random (e.g., to even out the load from reporting from several sensors), in response to a triggering event (e.g., when moisture is detected an alert is sent), in response to a request (e.g., a user initiated request), or a continuous stream (e.g., a live video feed of a patient).

[0302] As another example, a UE comprises an actuator, a motor, or a switch, related to a communication interface configured to receive wireless input from a network node via a wireless connection. In response to the received wireless input the states of the actuator, the motor, or the switch may change. For example, the UE may comprise a motor that adjusts the control surfaces or rotors of a drone in flight according to the received input or to a robotic arm performing a medical procedure according to the received input.

[0303] A UE, when in the form of an Internet of Things (loT) device, may be a device for use in one or more application domains, these domains comprising, but not limited to, city wearable technology, extended industrial application and healthcare. Non-limiting examples of such an loT device are a device which is or which is embedded in: a connected refrigerator or freezer, a TV, a connected lighting device, an electricity meter, a robot vacuum cleaner, a voice controlled smart speaker, a home security camera, a motion detector, a thermostat, a smoke detector, a door / window sensor, a flood / moisture sensor, an electrical door lock, a connected doorbell, an air conditioning system like a heat pump, an autonomous vehicle, a surveillance system, a weather monitoring device, a vehicle parking monitoring device, an electric vehicle charging station, a smart watch, a fitness tracker, a head-mounted display for Augmented Reality (AR) or Virtual Reality (VR), a wearable for tactile augmentation or sensory enhancement, a water sprinkler, an animal- or item-tracking device, a sensor for monitoring a plant or animal, an industrial robot, an Unmanned Aerial Vehicle (UAV), and any kind of medical device, like a heart rate monitor or a remote controlled surgical robot. A UE in the form of an loT device comprises circuitry and / or software in dependence of the intended application of the loT device in addition to other components as described in relation to the UE 1100 shown in FIG. 11.

[0304] As yet another specific example, in an loT scenario, a UE may represent a machine or other device that performs monitoring and / or measurements, and transmits the results of such monitoring and / or measurements to another UE and / or a network node. The UE may in this case be an M2M device, which may in a 3 GPP context be referred to as an MTC device. As one particular example, the UE may implement the 3GPP NB-IoT standard. In other scenarios, a UE may represent a vehicle, such as a car, a bus, a truck, a ship and an airplane, or other equipment that is capable of monitoring and / or reporting on its operational status or other functions associated with its operation.

[0305] In practice, any number of UEs may be used together with respect to a single use case. For example, a first UE might be or be integrated in a drone and provide the drone’s speed information (obtained through a speed sensor) to a second UE that is a remote controller operating the drone. When the user makes changes from the remote controller, the first UE may adjust the throttle on the drone (e.g. by controlling an actuator) to increase or decrease the drone’s speed. The first and / or the second UE can also include more than one of the functionalities described above. For example, a UE might comprise the sensor and the actuator, and handle communication of data for both the speed sensor and the actuators.

[0306] FIG. 12 shows a network node 1200 in accordance with some embodiments. As used herein, network node refers to equipment capable, configured, arranged and / or operable to communicate directly or indirectly with a UE and / or with other network nodes or equipment, in a telecommunication network. Examples of network nodes include, but are not limited to, access points (APs) (e.g., radio access points), base stations (BSs) (e.g., radio base stations, Node Bs, evolved Node Bs (eNBs) and NRNodeBs (gNBs)).

[0307] Base stations may be categorized based on the amount of coverage they provide (or, stated differently, their transmit power level) and so, depending on the provided amount of coverage, may be referred to as femto base stations, pico base stations, micro base stations, or macro base stations. A base station may be a relay node or a relay donor node controlling a relay. A network node may also include one or more (or all) parts of a distributed radio base station such as centralized digital units and / or remote radio units (RRUs), sometimes referred to as Remote Radio Heads (RRHs). Such remote radio units may or may not be integrated with an antenna as an antenna integrated radio. Parts of a distributed radio base station may also be referred to as nodes in a distributed antenna system (DAS).

[0308] Other examples of network nodes include multiple transmission point (multi-TRP) 5G access nodes, multi -standard radio (MSR) equipment such as MSR BSs, network controllers such as radio network controllers (RNCs) or base station controllers (BSCs), base transceiver stations (BTSs), transmission points, transmission nodes, multi -cell / multicast coordination entities (MCEs), Operation and Maintenance (O&M) nodes, Operations Support System (OSS) nodes, Self-Organizing Network (SON) nodes, positioning nodes (e.g., Evolved Serving Mobile Location Centers (E-SMLCs)), and / or Minimization of Drive Tests (MDTs).

[0309] The network node 1200 includes a processing circuitry 1202, a memory 1204, a communication interface 1206, and a power source 1208. The network node 1200 may be composed of multiple physically separate components (e.g., a NodeB component and a RNC component, or a BTS component and a BSC component, etc.), which may each have their own respective components. In certain scenarios in which the network node 1200 comprises multiple separate components (e.g., BTS and BSC components), one or more of the separate components may be shared among several network nodes. For example, a single RNC may control multiple NodeBs. In such a scenario, each unique NodeB and RNC pair, may in some instances be considered a single separate network node. In some embodiments, the network node 1200 may be configured to support multiple radio access technologies (RATs). In such embodiments, some components may be duplicated (e.g., separate memory 1204 for different RATs) and some components may be reused (e.g., a same antenna 1210 may be shared by different RATs). The network node 1200 may also include multiple sets of the various illustrated components for different wireless technologies integrated into network node 1200, for example GSM, WCDMA, LTE, NR, WiFi, Zigbee, Z-wave, LoRaWAN, Radio Frequency Identification (RFID) or Bluetooth wireless technologies. These wireless technologies may be integrated into the same or different chip or set of chips and other components within network node 1200.

[0310] The processing circuitry 1202 may comprise a combination of one or more of a microprocessor, controller, microcontroller, central processing unit, digital signal processor, application-specific integrated circuit, field programmable gate array, or any other suitable computing device, resource, or combination of hardware, software and / or encoded logic operable to provide, either alone or in conjunction with other network node 1200 components, such as the memory 1204, to provide network node 1200 functionality.

[0311] In some embodiments, the processing circuitry 1202 includes a system on a chip (SOC). In some embodiments, the processing circuitry 1202 includes one or more of radio frequency (RF) transceiver circuitry 1212 and baseband processing circuitry 1214. In some embodiments, the radio frequency (RF) transceiver circuitry 1212 and the baseband processing circuitry 1214 may be on separate chips (or sets of chips), boards, or units, such as radio units and digital units. In alternative embodiments, part or all of RF transceiver circuitry 1212 and baseband processing circuitry 1214 may be on the same chip or set of chips, boards, or units.

[0312] The memory 1204 may comprise any form of volatile or non-volatile computer-readable memory including, without limitation, persistent storage, solid-state memory, remotely mounted memory, magnetic media, optical media, random access memory (RAM), read-only memory (ROM), mass storage media (for example, a hard disk), removable storage media (for example, a flash drive, a Compact Disk (CD) or a Digital Video Disk (DVD)), and / or any other volatile or non-volatile, non- transitory device-readable and / or computer-executable memory devices that store information, data, and / or instructions that may be used by the processing circuitry 1202. The memory 1204 may store any suitable instructions, data, or information, including a computer program, software, an application including one or more of logic, rules, code, tables, and / or other instructions capable of being executed by the processing circuitry 1202 and utilized by the network node 1200. The memory 1204 may be used to store any calculations made by the processing circuitry 1202 and / or any data received via the communication interface 1206. In some embodiments, the processing circuitry 1202 and memory 1204 is integrated.

[0313] The communication interface 1206 is used in wired or wireless communication of signaling and / or data between a network node, access network, and / or UE. As illustrated, the communication interface 1206 comprises port(s) / terminal(s) 1216 to send and receive data, for example to and from a network over a wired connection. The communication interface 1206 also includes radio front-end circuitry 1218 that may be coupled to, or in certain embodiments a part of, the antenna 1210. Radio front-end circuitry 1218 comprises filters 1220 and amplifiers 1222. The radio front-end circuitry 1218 may be connected to an antenna 1210 and processing circuitry 1202. The radio front-end circuitry may be configured to condition signals communicated between antenna 1210 and processing circuitry 1202. The radio front-end circuitry 1218 may receive digital data that is to be sent out to other network nodes or UEs via a wireless connection. The radio front-end circuitry 1218 may convert the digital data into a radio signal having the appropriate channel and bandwidth parameters using a combination of filters 1220 and / or amplifiers 1222. The radio signal may then be transmitted via the antenna 1210. Similarly, when receiving data, the antenna 1210 may collect radio signals which are then converted into digital data by the radio front-end circuitry 1218. The digital data may be passed to the processing circuitry 1202. In other embodiments, the communication interface may comprise different components and / or different combinations of components.

[0314] In certain alternative embodiments, the network node 1200 does not include separate radio frontend circuitry 1218, instead, the processing circuitry 1202 includes radio front-end circuitry and is connected to the antenna 1210. Similarly, in some embodiments, all or some of the RF transceiver circuitry 1212 is part of the communication interface 1206. In still other embodiments, the communication interface 1206 includes one or more ports or terminals 1216, the radio front-end circuitry 1218, and the RF transceiver circuitry 1212, as part of a radio unit (not shown), and the communication interface 1206 communicates with the baseband processing circuitry 1214, which is part of a digital unit (not shown).

[0315] The antenna 1210 may include one or more antennas, or antenna arrays, configured to send and / or receive wireless signals. The antenna 1210 may be coupled to the radio front-end circuitry 1218 and may be any type of antenna capable of transmitting and receiving data and / or signals wirelessly. In certain embodiments, the antenna 1210 is separate from the network node 1200 and connectable to the network node 1200 through an interface or port.

[0316] The antenna 1210, communication interface 1206, and / or the processing circuitry 1202 may be configured to perform any receiving operations and / or certain obtaining operations described herein as being performed by the network node. Any information, data and / or signals may be received from a UE, another network node and / or any other network equipment. Similarly, the antenna 1210, the communication interface 1206, and / or the processing circuitry 1202 may be configured to perform any transmitting operations described herein as being performed by the network node. Any information, data and / or signals may be transmitted to a UE, another network node and / or any other network equipment.

[0317] The power source 1208 provides power to the various components of network node 1200 in a form suitable for the respective components (e.g., at a voltage and current level needed for each respective component). The power source 1208 may further comprise, or be coupled to, power management circuitry to supply the components of the network node 1200 with power for performing the functionality described herein. For example, the network node 1200 may be connectable to an external power source (e.g., the power grid, an electricity outlet) via an input circuitry or interface such as an electrical cable, whereby the external power source supplies power to power circuitry of the power source 1208. As a further example, the power source 1208 may comprise a source of power in the form of a battery or battery pack which is connected to, or integrated in, power circuitry. The battery may provide backup power should the external power source fail.

[0318] Embodiments of the network node 1200 may include additional components beyond those shown in FIG. 12 for providing certain aspects of the network node’s functionality, including any of the functionality described herein and / or any functionality necessary to support the subject matter described herein. For example, the network node 1200 may include user interface equipment to allow input of information into the network node 1200 and to allow output of information from the network node 1200. This may allow a user to perform diagnostic, maintenance, repair, and other administrative functions for the network node 1200.

[0319] FIG. 13 is a block diagram illustrating a virtualization environment 1300 in which functions implemented by some embodiments may be virtualized. In the present context, virtualizing means creating virtual versions of apparatuses or devices which may include virtualizing hardware platforms, storage devices and networking resources. As used herein, virtualization can be applied to any device described herein, or components thereof, and relates to an implementation in which at least a portion of the functionality is implemented as one or more virtual components. Some or all of the functions described herein may be implemented as virtual components executed by one or more virtual machines (VMs) implemented in one or more virtual environments 1300 hosted by one or more of hardware nodes, such as a hardware computing device that operates as a network node, UE, core network node, or host. Further, in embodiments in which the virtual node does not require radio connectivity (e.g., a core network node or host), then the node may be entirely virtualized.

[0320] Applications 1302 (which may alternatively be called software instances, virtual appliances, network functions, virtual nodes, virtual network functions, etc.) are run in the virtualization environment 1400 to implement some of the features, functions, and / or benefits of some of the embodiments disclosed herein.

[0321] Hardware 1304 includes processing circuitry, memory that stores software and / or instructions executable by hardware processing circuitry, and / or other hardware devices as described herein, such as a network interface, input / output interface, and so forth. Software may be executed by the processing circuitry to instantiate one or more virtualization layers 1306 (also referred to as hypervisors or virtual machine monitors (VMMs)), provide VMs 1308a and 1308b (one or more of which may be generally referred to as VMs 1308), and / or perform any of the functions, features and / or benefits described in relation with some embodiments described herein. The virtualization layer 1306 may present a virtual operating platform that appears like networking hardware to the VMs 1308.

[0322] The VMs 1308 comprise virtual processing, virtual memory, virtual networking or interface and virtual storage, and may be run by a corresponding virtualization layer 1306. Different embodiments of the instance of a virtual appliance 1302 may be implemented on one or more of VMs 1308, and the implementations may be made in different ways. Virtualization of the hardware is in some contexts referred to as network function virtualization (NFV). NFV may be used to consolidate many network equipment types onto industry standard high volume server hardware, physical switches, and physical storage, which can be located in data centers, and customer premise equipment.

[0323] In the context of NFV, a VM 1308 may be a software implementation of a physical machine that runs programs as if they were executing on a physical, non-virtualized machine. Each of the VMs 1308, and that part of hardware 1304 that executes that VM, be it hardware dedicated to that VM and / or hardware shared by that VM with others of the VMs, forms separate virtual network elements. Still in the context of NFV, a virtual network function is responsible for handling specific network functions that run in one or more VMs 1308 on top of the hardware 1304 and corresponds to the application 1302.

[0324] Hardware 1304 may be implemented in a standalone network node with generic or specific components. Hardware 1304 may implement some functions via virtualization. Alternatively, hardware 1304 may be part of a larger cluster of hardware (e.g. such as in a data center or CPE) where many hardware nodes work together and are managed via management and orchestration 1310, which, among others, oversees lifecycle management of applications 1302. In some embodiments, hardware 1304 is coupled to one or more radio units that each include one or more transmitters and one or more receivers that may be coupled to one or more antennas. Radio units may communicate directly with other hardware nodes via one or more appropriate network interfaces and may be used in combination with the virtual components to provide a virtual node with radio capabilities, such as a radio access node or a base station. In some embodiments, some signaling can be provided with the use of a control system 1312 which may alternatively be used for communication between hardware nodes and radio units.

[0325] Although the computing devices described herein (e.g., UEs, network nodes, hosts) may include the illustrated combination of hardware components, other embodiments may comprise computing devices with different combinations of components. It is to be understood that these computing devices may comprise any suitable combination of hardware and / or software needed to perform the tasks, features, functions and methods disclosed herein. Determining, calculating, obtaining or similar operations described herein may be performed by processing circuitry, which may process information by, for example, converting the obtained information into other information, comparing the obtained information or converted information to information stored in the network node, and / or performing one or more operations based on the obtained information or converted information, and as a result of said processing making a determination. Moreover, while components are depicted as single boxes located within a larger box, or nested within multiple boxes, in practice, computing devices may comprise multiple different physical components that make up a single illustrated component, and functionality may be partitioned between separate components. For example, a communication interface may be configured to include any of the components described herein, and / or the functionality of the components may be partitioned between the processing circuitry and the communication interface. In another example, non-computationally intensive functions of any of such components may be implemented in software or firmware and computationally intensive functions may be implemented in hardware.

[0326] In certain embodiments, some or all of the functionality described herein may be provided by processing circuitry executing instructions stored on in memory, which in certain embodiments may be a computer program product in the form of a non-transitory computer-readable storage medium. In alternative embodiments, some or all of the functionality may be provided by the processing circuitry without executing instructions stored on a separate or discrete device-readable storage medium, such as in a hard-wired manner. In any of those particular embodiments, whether executing instructions stored on a non-transitory computer-readable storage medium or not, the processing circuitry can be configured to perform the described functionality. The benefits provided by such functionality are not limited to the processing circuitry alone or to other components of the computing device, but are enjoyed by the computing device as a whole, and / or by end users and a wireless network generally.

Claims

CLAIMS1. A method (300) performed by a terminal device in a communication network, comprising: obtaining (S302) a first synchronization signal block measurement timing configuration, SMTC, before or after changing from a first cell to a second cell; adjusting (S304) an offset parameter in the first SMTC, based at least on a propagation delay in the second cell; and performing (S306) measurement in the second cell, based on the first SMTC with the adjusted offset parameter.

2. The method (300) according to claim 1, wherein a first synchronization signal block, SSB, is configured for the first cell, and a second SSB is configured for the second cell; and wherein the first SSB and the second SSB occupy the same time position in schedule, or the first SSB and the second SSB have different SSB indices, or the second SSB is a time shifted version of the first SSB.

3. The method (300) according to claim 2, further comprising: adjusting (S308) the offset parameter in the first SMTC, further based on a time offset in schedule between the first SSB and the second SSB.

4. The method (300) according to claim 2, wherein the offset parameter in the first SMTC is provided by the first cell or the second cell, based on the time offset in schedule between the first SSB and the second SSB.

5. The method (300) according to any of claims 1 to 4, further comprising: performing (S310) measurement in the second cell, based on the first SMTC without adjusting the offset parameter based on the propagation delay, in response to an indication from the first cell or the second cell.

6. The method (300) according to any of claims 1 to 5, further comprising: obtaining (S312) a second SMTC; and performing (S314) measurement, based on the second SMTC.

7. The method (300) according to claim 6, further comprising: transmitting (S316) a request for the first SMTC and / or the second SMTC.

8. The method (300) according to claim 6 or 7, wherein the first SMTC is obtained by the terminal device in a common control signaling; and wherein the second SMTC is obtained by the terminal device in a dedicated signaling.

9. The method (300) according to claim 8, wherein the first SMTC is obtained by the terminal device in a system information block, SIB.

10. The method (300) according to claim 9, wherein the terminal device obtains the SIB regardless of whether an indication about a change in the SIB exists.

11. The method (300) according to claim 6 or 7, wherein the first SMTC is obtained by the terminal device in a dedicated signaling before the changing; and wherein the second SMTC is obtained by the terminal device in a dedicated signaling after the changing.

12. The method (300) according to any of claims 1 to 11, wherein an indication from the first cell or the second cell indicates the terminal device at least one of whether to adjust an offset parameter in the first SMTC based on a propagation delay in the second cell; using the first SMTC to perform measurement in the second cell; or using another SMTC to perform measurement in the second cell; and wherein the indication is implicit or explicit.

13. The method (300) according to any of claims 1 to 12, wherein the terminal device is in a RRC CONNECTED state in the first cell and switches to the second cell; or wherein the terminal device is in a RRC IDLE state or an INACTIVE state and reselects the second cell.

14. The method (300) according to any of claims 1 to 13, wherein terminal device changes from the first cell to the second cell without L3 mobility.

15. The method (300) according to any of claims 1 to 14, wherein the first cell and the second cell have the same physical cell identity.

16. The method (300) according to any of claims 1 to 15, wherein the first cell is provided by a first satellite and / or the second cell is provided by a second satellite.

17. A method (400) performed by a network node in a communication network, comprising:transmitting (S402), a first synchronization signal block measurement timing configuration, SMTC, to a terminal device, before or after the terminal device changing from a first cell to a second cell; and indicating (S404) the terminal device whether to adjust an offset parameter in the first SMTC.

18. The method (400) according to claim 17, wherein the network node indicates the terminal device whether to adjust the offset parameter in the first SMTC based on a propagation in the second cell; wherein a first synchronization signal block, SSB, is configured for the first cell, and a second SSB is configured for the second cell; and wherein the first SSB and the second SSB occupy the same time position in schedule, or the first SSB and the second SSB have different SSB indices, or the second SSB is a time shifted version of the first SSB.

19. The method (400) according to claim 18, further comprising: providing (S406) the offset parameter in the first SMTC, based on the time offset in schedule between the first SSB and the second SSB.

20. The method (400) according to any of claims 17 to 19, further comprising: transmitting (S408), to the terminal device, a second SMTC.

21. The method (400) according to claim 20, further comprising: receiving (S410), from the terminal device, a request for the first SMTC and / or the second SMTC.

22. The method (400) according to claim 20 or 21, wherein the first SMTC is included in a common control signaling; and wherein the second SMTC is included in a dedicated signaling.

23. The method (400) according to claim 22, wherein the first SMTC is included in a system information block, SIB.

24. The method (400) according to claim 23, wherein the terminal device obtains the SIB regardless of whether an indication about a change in the SIB exists.

25. The method (400) according to claim 20 or 21, wherein the first SMTC is obtained by the terminal device in a dedicated signaling before the changing; and wherein the second SMTC is obtained by the terminal device in a dedicated signaling after the changing.

26. The method (400) according to any of claims 17 to 25, wherein the terminal device is in a RRC CONNECTED state in the first cell and switches to the second cell; or wherein the terminal device is in a RRC IDLE state or an INACTIVE state and reselects the second cell.

27. The method (400) according to any of claims 17 to 26, wherein terminal device changes from the first cell to the second cell without L3 mobility.

28. The method (400) according to any of claims 17 to 27, wherein the first cell and the second cell have the same physical cell identity, PCI.

29. The method (400) according to any of claims 17 to 28, wherein the first cell is provided by a first satellite and / or the second cell is provided by a second satellite; and wherein the network node is a base station connected to the first satellite and / or the second satellite.

30. The method (400) according to claim 28 or 29, further comprising: determining (S412) whether a condition related to served terminal devices is satisfied; and when the condition is satisfied, performing (S414) at least one of the following actions: disabling the changing from the first cell to the second cell, when the second cell has the same PCI with the first cell; configuring a SSB in the first cell to use a different frequency than a SSB in the second cell; configuring the SSB in the second cell to be sent upon or after stopping the SSB in the first cell; or releasing terminal devices served by the network node and not supporting to obtain SSB information about the second cell.

31. The method (400) according to claim 30, wherein the condition comprises at least one of: a number of RRC CONNECTED terminal devices served by the network node and not supporting to obtain SSB information about the second cell after the changing exceeds a threshold; and / or a ratio of RRC CONNECTED terminal devices served by the network node and not supporting to obtain SSB information about the second cell after the changing exceeds another threshold.

32. The method (400) according to claim 30 or 31, wherein the condition is applied to terminal devices with quality of service, QoS, requirements.

33. An apparatus (50) for a terminal device in a communication network, comprising: a processor (501); and a memory (502), the memory (502) containing instructions executable by the processor (501), whereby the apparatus (50) for the terminal device is operative for: obtaining a first synchronization signal block measurement timing configuration, SMTC, before or after changing from a first cell to a second cell; adjusting an offset parameter in the first SMTC, based at least on a propagation delay in the second cell; and performing measurement in the second cell, based on the first SMTC with the adjusted offset parameter.

34. The apparatus (50) according to claim 33, wherein the apparatus (50) is further operative to perform the method according to any of claims 2 to 16.

35. An apparatus (60) for a network node in a communication network, comprising: a processor (601); and a memory (602), the memory (602) containing instructions executable by the processor (601), whereby the apparatus (60) for the network node is operative for: transmitting, a first synchronization signal block measurement timing configuration, SMTC, to a terminal device, before or after the terminal device changing from a first cell to a second cell; and indicating the terminal device whether to adjust an offset parameter in the first SMTC.

36. The apparatus (60) according to claim 35, wherein the apparatus (60) is further operative to perform the method according to any of claims 18 to 32.

37. A computer-readable storage medium (70) storing instructions (701), which when executed by at least one processor, cause the at least one processor to perform the method according to any one of claims 1 to 32.

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