Communication equipment, infrastructure equipment and method for wireless communication network

Abstract

A method for infrastructure equipment of a wireless communication network, the method comprising: receiving a request to establish a connection from a communication device in a first cell; and in response to receiving the request, selecting a second cell as a next serving cell for the communication device and sending an indication of an identity of the second cell to the communication device.

Description

Technical Field

[0001] The present disclosure relates to a communication device, an infrastructure device and a method for cell change of a communication device in a cell of a wireless communication network provided by a non-terrestrial network portion.

[0002] This application claims the Paris Convention priority of European Patent Application No. EP18189822, the entire contents of which are incorporated herein by reference. Background Art

[0003] The background description provided herein is for the purpose of presenting the context of the present disclosure in general. Within the scope described in this background technology section, the work of the inventors, as well as aspects of the description that may not conform to the prior art at the time of submission, are neither explicitly nor implicitly admitted as prior art against the present invention.

[0004] Recent generations of mobile telecommunication systems, such as those based on the UMTS and Long Term Evolution (LTE) architectures defined by the Third Generation Partnership Project (3GPP), are capable of supporting a wider range of services than the simple voice and messaging services provided by previous generations of mobile telecommunication systems. For example, utilizing the improved radio interface and enhanced data rates provided by LTE systems, users are able to enjoy high data rate applications such as mobile video streaming and mobile video conferencing, which were previously only available over fixed line data connections. In addition to supporting these types of more complex services and devices, new generation mobile telecommunication systems are also proposed to support less complex services and devices that take advantage of the reliable and wide coverage of new generation mobile telecommunication systems without necessarily relying on the high data rates available in such systems.

[0005] Thus, future wireless communication networks will be expected to routinely and efficiently support a wider range of devices associated with a wider range of data traffic specifications and types than currently optimized systems support. For example, future wireless communication networks are expected to efficiently support communications with devices including reduced complexity devices, machine type communication (MTC) devices, high resolution video displays, virtual reality headsets, and the like. Some of these different types of devices may be deployed in very large numbers, such as low complexity devices used to support the "Internet of Things", and may typically be associated with the transmission of relatively small amounts of data with relatively high delay tolerances.

[0006] In view of this, future wireless communication networks, such as those which may be referred to as 5G or new radio (NR) systems / new radio access technology (RAT) systems, as well as future iterations / releases of existing systems, are expected to effectively support connectivity for a wide range of devices associated with different applications and data service specifications of different characteristics.

[0007] In this regard, an example area of ​​current interest consists of so-called non-terrestrial networks, or NTNs for short. 3GPP has proposed in Release 15 of the 3GPP specifications to develop technologies for providing coverage via one or more antennas mounted on airborne or spaceborne vehicles [1].

[0008] Non-terrestrial networks can provide service in areas not covered by terrestrial cellular networks (i.e., those areas that provide coverage via ground-based antennas, such as isolated or remote areas on aircraft or ships), or can provide enhanced service in other areas. The extended coverage that can be achieved through non-terrestrial networks can provide service continuity for machine-to-machine (M2M) or "Internet of Things" (IoT) devices, or passengers on mobile platforms (e.g., passenger vehicles such as aircraft, ships, high-speed trains, or buses). Using non-terrestrial networks to provide multicast / broadcast resources for data delivery can produce other benefits.

[0009] The use of different types of network infrastructure equipment and the demand for coverage enhancement bring new challenges that need to be addressed to efficiently handle communications in wireless telecommunication systems. Summary of the invention

[0010] The present disclosure may help solve or alleviate at least some of the problems discussed above.

[0011] According to the present technology, a method for infrastructure equipment of a wireless communication network is provided, the method comprising: receiving a request to enter a connection mode from a communication device in a first cell; and in response to receiving the request, selecting a second cell to become the next service cell of the communication device, and sending an indication of an identification of the second cell to the communication device.

[0012] Embodiments of the present technique may provide an arrangement that may distribute mobility procedure signaling more evenly over time and / or may reduce the peak rate of mobility-related signaling.

[0013] Various aspects and features of the present disclosure are defined in the following claims.

[0014] It should be understood that the foregoing general description and the following detailed description are exemplary rather than limiting of the present technology. The described embodiments and further advantages will be best understood by reference to the following detailed description taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] A more complete appreciation of the present disclosure and its many attendant advantages will thus be readily obtained as the present disclosure will be better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference numerals designate like or corresponding parts throughout the several views, and in which:

[0016] Figure 1 schematically represents some aspects of an LTE-type wireless telecommunications system that may be configured to operate in accordance with exemplary embodiments of the present disclosure;

[0017] Figure 2 schematically represents some exemplary aspects of a new radio access technology (RAT) wireless communication network that may be configured to operate in accordance with embodiments of the present disclosure;

[0018] Figure 3 schematically represents some exemplary aspects of a wireless telecommunication system according to an embodiment of the present disclosure;

[0019] Figure 4 illustrates the movement of a communication device, a non-terrestrial network portion, and a cell according to an embodiment of the present disclosure;

[0020] Figure 5 is a process diagram and a message sequence chart illustrating an embodiment of the present disclosure. DETAILED DESCRIPTION

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

[0022] The network 100 includes a plurality of base stations 101 connected to a core network portion 102. Each base station provides a coverage area 103 (e.g., a cell) within which data can be communicated to and from terminal devices 104. Data is transmitted from the base stations 101 to the terminal devices 104 within their respective coverage areas 103 via a radio downlink. Data is transmitted from the terminal devices 104 to the base stations 101 via a radio uplink. The core network portion 102 routes data to and from the terminal devices 104 via the respective base stations 101 and provides functions such as authentication, mobility management, charging, etc. The terminal devices may also be referred to as mobile stations, user equipment (UE), user terminals, mobile radios, communication devices, etc. A base station as an example of a network infrastructure device / network access node may also be referred to as a transceiver station / nodeB / e-nodeB, g-nodeB, etc. In this regard, different terms are often associated with different generations of wireless telecommunication systems for elements providing broadly comparable functions. However, exemplary embodiments of the present disclosure may be implemented equally in different generations of wireless telecommunication systems, and for simplicity, certain terms may be used regardless of the underlying network architecture. That is, the use of specific terms with respect to certain example implementations is not intended to indicate that these implementations are limited to a certain generation of networks that may be most associated with the specific terms.

[0023] Figure 2 is a schematic diagram showing a network architecture of a new RAT wireless communication network / system 300 based on a previously proposed method, which may also be adapted to provide functionality according to the disclosed embodiments described herein. Figure 2 The new RAT network 300 shown includes a first communication cell 301 and a second communication cell 302. Each communication cell 301, 302 includes a control node (centralized unit) 321, 322 that communicates with a core network component 310 via corresponding wired or wireless links 351, 352. Each control node 321, 322 also communicates with multiple distributed units (radio access nodes / remote transmission and reception points (TRP)) 311, 312 in their respective cells. Similarly, these communications can be through corresponding wired or wireless links. Distributed units 311, 312 are responsible for providing a radio access interface for terminal devices connected to the network. Each distributed unit 311, 312 has a coverage area (radio access coverage area) 341, 342, which together define the coverage range of each communication cell 301, 302.

[0024] Compared with the wide range of top-level functions, Figure 2 The core network components 310 of the new RAT communication network shown can be broadly considered to be similar to Figure 1The core network 102 shown corresponds to the core network 102, and the corresponding control nodes 321, 322 and their associated distributed units / TRPs 311, 312 can be broadly considered to provide Figure 1 The term network infrastructure equipment / access node may be used to include these elements of the wireless communication system and more traditional base station type elements. Depending on the existing application, the responsibility for scheduling the transmissions scheduled on the radio interface between the various distributed units and the terminal devices may be assumed by the control node / centralized unit and / or the distributed units / TRP.

[0025] Figure 2 301. A terminal device 400 is shown in FIG. 300 within the coverage area of ​​a first communication cell 301. Thus, the terminal device 400 may exchange signaling with a first control node 321 in the first communication cell via one of the distributed units 311 associated with the first communication cell 301. In some cases, communications for a given terminal device are routed through only one of the distributed units, but it should be understood that in some other implementations, such as in soft handover scenarios and other scenarios, communications associated with a given terminal device may be routed through more than one distributed unit. The particular distributed unit through which the terminal device is currently connected to the associated control node may be referred to as the active distributed unit of the terminal device. Thus, the active subset of distributed units for the terminal device may include one or more distributed units (TRPs). The control node 321 is responsible for determining which of the distributed units 311 across the first communication cell 301 is responsible for radio communications with the terminal device 400 at any given time (i.e., which of the distributed units is the current active distributed unit of the terminal device). Typically, this will be based on measurements of radio channel conditions between the terminal device 400 and the corresponding distributed units in the distributed units 311. In this regard, it will be appreciated that the subset of distributed units in a cell that is currently active for a terminal device will depend at least in part on the location of the terminal device within the cell (as this contributes significantly to the radio channel conditions that exist between the terminal device and a respective one of the distributed units).

[0026] exist Figure 2 In the example, for simplicity, two communication cells 301, 302 and one terminal device 400 are shown, but it should be understood that in practice, the system may include a plurality of terminal devices serving a greater number of communication cells (each communication cell is supported by a corresponding control node and a plurality of distributed units) for a greater number of terminal devices.

[0027] It should also be understood that Figure 2It only represents one example of the proposed architecture for a new RAT communication system, in which the method according to the principles described herein may be employed, and the functions disclosed herein may also be applied for wireless communication systems with different architectures.

[0028] Therefore, it is possible to configure the Figure 1 and Figure 2 The exemplary embodiments of the present disclosure discussed herein are implemented in a wireless telecommunications system / network (see the example architecture shown). It should be understood, therefore, that the particular wireless communication architecture in any given implementation is not of primary significance to the principles described herein. In this regard, the exemplary embodiments of the present disclosure may be generally described in the context of communications between network infrastructure equipment / access nodes and terminal devices, wherein the specific nature of the network infrastructure equipment / access nodes and terminal devices will depend on the network infrastructure used for the implementation at hand. For example, in some scenarios, the network infrastructure equipment / access nodes may include base stations, such as Figure 1 The LTE type base station 101 shown is suitable for providing the functionality of the principles described herein, and in other examples, the network infrastructure equipment / access node may include Figure 2 The type of control cells / control nodes 321, 322 and / or TRPs 311, 312 shown are suitable for providing the functionality of the principles described herein.

[0029] In wireless telecommunications networks, such as LTE type or 5G type networks, there are different radio resource control (RRC) modes for terminal devices. For example, RRC idle mode (RRC_IDLED) and RRC connected mode (RRC_CONNECTED) are generally supported. A terminal device in idle mode can transition to RRC connected mode, for example because it needs to send uplink data or respond to a paging request by performing a random access procedure. The random access procedure involves the terminal device sending a preamble on a physical random access channel (RACH), so the procedure is usually referred to as a RACH or PRACH step / procedure.

[0030] Therefore, the traditional way in which a terminal device (UE) in RRC idle mode exchanges data with a network involves the terminal device first performing an RRC connection procedure (random access procedure) with the network. The RRC connection procedure includes the UE initially sending a random access request message (which may be autonomously triggered by the UE determining that it has data to send to the network or in response to the network instructing the UE to connect to the network). This is followed by an exchange of RRC control messages between the network and the UE, including: "Message 2" or a random access response message; "Message 3", sent by the UE and including an RRC message sent by the UE requesting to establish, reestablish, or resume an RRC connection; and "Message 4" sent by the network, which includes an RRC message sent in response to "Message 3". It should be understood that a large number of different possible Message 3 and Message 4 messages may be used as part of the RACH procedure. As part of the random access procedure, contention resolution may be used to avoid the possibility of multiple communication devices determining that they have successfully established an RRC connection; to this end, each Message 3 may include an identifier of a communication device, and Message 4 may include an identifier corresponding to the successful communication device.

[0031] Message 3 may include a non-access stratum (NAS) message having a core network entity as its intended destination. For example, the NAS message may be an initial user equipment (UE) message.

[0032] After establishing the RRC connection and exchanging relevant data, the UE may then perform an RRC disconnection and move back to idle mode to save power.

[0033] A wireless telecommunications network such as a 5G (NR) network may support an RRC Inactive (RRC_INACTIVE) mode in which, like the RRC Idle mode, it cannot send data but must transition to an RRC Connected mode in order to send or receive data. In both the RRC Inactive and RRC Idle modes, mobility (i.e., change of serving cell) is achieved by UE-based cell reselection according to parameters sent by the wireless telecommunications network. In the RRC Connected mode, mobility may be network controlled; that is, handover may be initiated by infrastructure equipment of the network. Handover may conventionally be initiated in response to, for example, a measurement report sent by a terminal device, which may indicate measurement results of downlink signals sent by the network in both the serving cell and one or more neighboring (candidate) cells.

[0034] Measurements by a communications device of signals transmitted by infrastructure equipment that is generating cells other than the communications device's serving cell may be used to detect whether the communications device is within or close to the coverage area of ​​a different cell. Such signals may include an indication of the identity of the cell, so that if signals of multiple cells are transmitted on the same frequency, the communications device is able to determine to which cell or cells the transmission corresponds.

[0035] In addition to measurements used to determine whether the communications device is within or near the coverage of a non-serving cell, the communications device may perform measurements of signals transmitted by its serving cell in order to assess whether the current serving cell is still suitable.

[0036] For the purposes of autonomous (i.e., device-controlled) mobility, measurements may be made in idle mode (where the device is not actively sending or receiving data, and may not have an active connection to infrastructure associated with a serving cell). Measurements may additionally or alternatively be made in connected mode (where the device is actively sending or receiving data, and may have an active connection to infrastructure equipment associated with a serving cell). The results of the measurements made in connected mode may be sent to the serving infrastructure equipment in order to allow the wireless communication network to determine whether a cell change is necessary (and if so, to which new cell), and to initiate a network-controlled mobility procedure accordingly.

[0037] To support these measurements, the infrastructure equipment may transmit a reference signal continuously or periodically in each cell according to a predetermined transmission schedule on a frequency (or a frequency-centric band) configured by the wireless communication network operator.

[0038] The measurement of such signals (including decoding where applicable) may consume a significant amount of power, thereby impacting the cell lifetime of cell powered communication devices. Typically, the power consumption associated with such measurements may be more dependent on the number of different frequencies at which signals are to be received and decoded than on the number of cells being measured.

[0039] If the communications device is in any case performing measurements of its serving cell, the additional power consumption required to detect and measure additional cells using the same frequency as the serving cell may be less than the additional power consumption required to measure signals of other cells transmitted on different frequencies.

[0040] Conventionally, a communication device may receive from a serving network portion (e.g., infrastructure equipment) a list of "carrier" frequencies to be measured, which list may be specific to its serving cell and may or may not be specific to the communication device. The list of carrier frequencies may be accompanied by associated parameters, such as a priority associated with each frequency and measurement and reporting thresholds.

[0041] Since terrestrial networks are typically static, the list of carrier frequencies typically does not change over time and may be the same for all communication devices within a cell coverage area. Therefore, in order to minimize the communication resources used to send the list of carrier frequencies, the list may be broadcast periodically in the system information. Once a communication device has received system information associated with its serving cell, if the stored system information remains valid, the communication device does not need to receive (or attempt to decode) the system information again when the communication device is within the coverage area of ​​the serving cell. System information may typically provide information about the operation of the wireless communication network, particularly in the cell to which it is sent (or associated with it), and may not be specific to a particular communication device. System information may be broadcast according to a specific schedule and may therefore be received by multiple communication devices.

[0042] Alternatively, the list of carrier frequencies may be sent to a particular communication device when the particular communication device is in connected mode.

[0043] Exceptionally, in a conventional terrestrial network, system information may change (e.g., because new infrastructure equipment has been enabled, thereby providing one or more new cells in the area of ​​the serving cell). To trigger a communication device to refresh its stored system information, a paging message may be sent by the infrastructure equipment associated with the serving cell with an indication that the system information has changed. In response to receiving such an indication, the communication device may receive and decode the updated system information.

[0044] Figure 3 A wireless telecommunication system 200 according to an exemplary embodiment of the present disclosure is schematically shown. The wireless telecommunication system 200 in this example is broadly based on an LTE-type or 5G-type architecture. Many aspects of the operation of the wireless telecommunication system / network 200 are known and understood and are not described in detail herein for the sake of brevity. Aspects of the operation of the wireless telecommunication system 200 not specifically described herein may be implemented in accordance with any known technology, such as in accordance with current LTE standards or proposed 5G standards.

[0045] The wireless telecommunications system 200 comprises a core network portion 102 coupled to a radio network portion (which may be a 4G core network or a 5G core network). The radio network portion comprises a base station (g-node B) 101 coupled to a non-terrestrial network portion 308. The non-terrestrial network portion 308 may be an example of infrastructure equipment.

[0046] The non-terrestrial network portion 308 may be installed on a satellite vehicle or an airborne vehicle.

[0047] The non-terrestrial network portion 308 is also coupled to the communication devices 208 located within the cell 202 through a wireless access interface provided by the wireless communication link 206. For example, the cell 202 may correspond to the coverage area of ​​a spot beam generated by the non-terrestrial network portion 308.

[0048] The boundaries of the cell 202 may depend on the altitude of the non-terrestrial network portion 308 and the configuration of one or more antennas of the non-terrestrial network portion 308 through which the non-terrestrial network portion 308 transmits and receives signals over the wireless access interface.

[0049] The non-terrestrial network portion 308 may be a satellite in orbit relative to the earth, or may be mounted on such a satellite. For example, the satellite may be in a geostationary orbit such that the non-terrestrial network portion 308 does not substantially move relative to a fixed point on the surface of the earth. The geostationary orbit may be approximately 36,000 kilometers above the earth's equator. Alternatively, the satellite may be in a non-geostationary orbit such that the non-terrestrial network portion 308 moves relative to a fixed point on the surface of the earth.

[0050] The non-ground network portion 308 may be an onboard vehicle, such as an aircraft, or may be installed on such a vehicle. The onboard vehicle (and therefore the non-ground network portion 308) may be stationary relative to the Earth's surface (e.g., the non-ground network portion 308 may be attached to, or form part of, a stationary balloon structure that is tethered to a fixed point on the Earth's surface) or may be mobile relative to the Earth's surface.

[0051] exist Figure 3 , the base station 101 is shown as being ground-based and coupled to the non-terrestrial network portion 308 via the wireless communication link 204. The non-terrestrial network portion 308 receives a signal representing downlink data sent by the base station 101 on the wireless communication link 204, and based on the received signal, sends a signal representing the downlink data via the wireless communication link 206 that provides a wireless access interface for the communication device 208. Similarly, the non-terrestrial network portion 308 receives a signal representing uplink data sent by the communication device 208 via the wireless access interface including the wireless communication link 206, and sends a signal representing the uplink data to the base station 101 on the wireless communication link 204.

[0052] In some embodiments, the wireless communication links 204, 206 operate at the same frequency; in some embodiments, the wireless communication links 204, 206 operate at different frequencies.

[0053] The extent to which the non-terrestrial network portion 308 processes received signals may depend on the processing capabilities of the non-terrestrial network portion 308. For example, the non-terrestrial network portion 308 may receive signals representing downlink data over the wireless communication link 204, amplify those signals, and (if necessary) remodulate those signals onto an appropriate carrier frequency for onward transmission over the wireless access interface provided by the wireless communication link 206.

[0054] Alternatively, the non-terrestrial network portion 308 can be configured to decode a signal representing downlink data received on the wireless communication link 204 into unencoded downlink data, re-encode the downlink data and modulate the encoded downlink data onto an appropriate carrier frequency for continued transmission over the wireless access interface provided by the wireless communication link 206.

[0055] In some embodiments, the non-terrestrial network portion 308 may be configured to perform some functions traditionally performed by the base station 101. In particular, delay-sensitive functions (e.g., confirming receipt of uplink data, or responding to a RACH request according to some embodiments of the present technology) may be performed by the non-terrestrial network portion 308 instead of by the base station 101.

[0056] In some embodiments, base station 101 may be co-located with non-terrestrial network portion 308; for example, both may be installed on the same satellite vehicle or airborne vehicle, and a physical (e.g., wired or optical fiber) connection may exist on the satellite vehicle or airborne vehicle to provide coupling between base station 101 and non-terrestrial network portion 308. In some embodiments, a wireless communication link between base station 101 and a ground station (not shown) may provide connectivity between base station 101 and core network portion 102.

[0057] Figure 3 The communication device 208 shown in FIG. 2 may generally correspond to Figure 1 The terminal device 104 or Figure 2 Additionally or alternatively, the communication device 208 may be configured to act as a relay node. That is, it may provide access to the wireless access interface via the wireless access interface. Figure 3 The wireless access interface provided by the communication device 208 for providing services and connections to the terminal device may substantially conform to the standard of the wireless access interface generated by the base station according to a standard such as the LTE standard or the 5G standard. Therefore, data may be sent by the terminal device to the communication device 208 and may be sent by the communication device 208 to the terminal device according to a conventional technique for sending data to a conventional base station or a conventional relay node.

[0058] Clearly, many scenarios can be envisioned where the combination of the communication device 208 and the non-terrestrial network portion 308 can provide enhanced services to end users. For example, the communication device 208 can be installed on a passenger vehicle, such as a bus or train, that travels through rural areas where coverage of ground base stations may be limited. Terminal devices on the vehicle can obtain services via the communication device 208 acting as a relay, which is coupled to the non-terrestrial network portion 308.

[0059] It is necessary to ensure that the connectivity of the communication device 208 with the base station 101 is maintained as a result of the movement of the communication device 208, the movement of the non-terrestrial network portion 308 (relative to the ground), or both. According to conventional cellular communication techniques, the decision to change the serving cell of the communication device 208 may be based on measurements of one or more characteristics of the radio frequency communication channel, such as signal strength measurements or signal quality measurements. In a terrestrial communication network, such measurements may effectively provide an indication that the communication device 208 is at or near the edge of a cell coverage area, since, for example, path loss may be widely related to the distance from the base station.

[0060] However, the inventors of the present technology have recognized that such conventional mobility techniques may not be suitable for communication devices served by cells generated by beam transmissions from non-terrestrial network portions, such as cell 202 generated by non-terrestrial network portion 308. In particular, in situations where a large number of communication devices, such as communication device 208, are located in close proximity, there may be a need to complete a mobility procedure in a short duration.

[0061] Another disadvantage of conventional techniques may be that cell changes occur at a relatively high rate for a communication device 208 that obtains service from one or more non-terrestrial network portions. For example, when the non-terrestrial network portion 308 is mounted on a satellite in low earth orbit (LEO), the non-terrestrial network portion 308 may complete an earth orbit in approximately 90 minutes; the coverage of cells generated by the non-terrestrial network portion 308 will move very quickly relative to a fixed observation point on the earth's surface.

[0062] Similarly, it is contemplated that the communication device 208 may be mounted on the airborne vehicle itself having a ground speed of several hundred kilometers per hour.

[0063] These shortcomings can be overcome by embodiments of the present technology, according to which infrastructure equipment of a wireless telecommunications network receives a request to enter a connected mode from a communication device in a first cell; and in response to receiving the request, selects a second cell as the next serving cell for the communication device, and sends an indication of an identification of the second cell to the communication device.

[0064] like Figure 3 As shown, the base station 101 includes a transceiver circuit 101a (which may also be referred to as a transceiver / transceiver unit) for sending and receiving wireless signals and a processor circuit 101b (which may also be referred to as a processor / processor unit) configured to control the base station 101 to operate according to the embodiments of the present disclosure described herein. The processor circuit 101b may include various sub-units / sub-circuits for providing the desired functions further explained herein. These sub-units may be implemented as discrete hardware elements, or as functions of appropriately configured processor circuits. Therefore, the processor circuit 101b may include circuits that are appropriately configured / programmed to provide the desired functions described herein using conventional programming / configuration techniques for devices in wireless telecommunications systems. For ease of representation, the transceiver circuit 101a and the processor circuit 101b are shown in FIG. Figure 3 1 and 2. The non-terrestrial base station 101 is shown as a separate element in FIG. However, it will be appreciated that the functionality of these circuit elements may be provided in a variety of different ways, such as using one or more appropriately programmed programmable computers, or one or more appropriately configured application specific integrated circuits / circuits / chips / chip sets. It will be appreciated that the non-terrestrial base station 101 will typically include various other elements associated with its operational functionality.

[0065] The non-terrestrial network portion 308 includes a transceiver circuit 308a (which may also be referred to as a transceiver / transceiver unit) for sending and receiving wireless signals and a processor circuit 308b (which may also be referred to as a processor / processor unit) configured to control the non-terrestrial network portion 308. The processor circuit 308b may include various sub-units / sub-circuits for providing functionality as further explained herein. These sub-units may be implemented as discrete hardware elements, or as functions of appropriately configured processor circuits. Thus, the processor circuit 308b may include circuits that are appropriately configured / programmed to provide the desired functionality using conventional programming / configuration techniques for devices in wireless telecommunications systems. For ease of presentation, the transceiver circuit 308a and the processor circuit 308b are shown in FIG. Figure 3 Schematically shown as separate elements in FIG. However, it will be appreciated that the functionality of these circuit elements may be provided in a variety of different ways, such as using one or more appropriately programmed programmable computers, or one or more appropriately configured application specific integrated circuits / circuits / chips / chip sets. It will be appreciated that the non-terrestrial network portion 308 will typically include various other elements associated with its operational functionality.

[0066] The communication device 208 includes transceiver circuitry 208a (which may also be referred to as a transceiver / transceiver unit) for sending and receiving wireless signals. The communication device 208 is configured to provide connectivity via the non-terrestrial network portion 308. For example, the transceiver circuitry 208b may be adapted to the non-terrestrial network portion 308 according to the nature of the communication channel, which is characterized by high path loss and the absence of multipath.

[0067] The communication device 208 also includes a processor circuit 208b (which may also be referred to as a processor / processor unit) configured to control the communication device 208. The processor circuit 208b may include various sub-units / sub-circuits for providing the functionality as further explained herein. These sub-units may be implemented as discrete hardware elements, or as functions of appropriately configured processor circuits. Thus, the processor circuit 208b may include circuits that are appropriately configured / programmed to provide the desired functionality using conventional programming / configuration techniques for devices in wireless telecommunications systems. For ease of representation, the transceiver circuit 208a and the processor circuit 208b are shown in FIG. Figure 3 208 are schematically shown as separate elements. However, it will be appreciated that the functionality of these circuit elements may be provided in a variety of different ways, such as using one or more appropriately programmed programmable computers, or one or more appropriately configured application-specific integrated circuits / circuits / chips / chip sets. It will be appreciated that the communication device 208 will typically include various other elements associated with its operating functionality.

[0068] It will be appreciated that in practice, the radio network portion of the wireless communication network 200 may include multiple base stations and non-terrestrial network portions serving a larger number of communication devices across various communication cells.

[0069] As with a conventional mobile radio network, the communication device 208 is arranged to communicate data to and from the base station (transceiver station) 101. The base station 101 is in turn communicatively connected to one or more core network entities within a core network portion 102. The core network portion 102 may include an enhanced packet core (EPC) network, and may include a serving gateway S-GW (not shown for simplicity) arranged to perform routing and management of mobile communication services via the base station 101 to the communication device 208 in the wireless telecommunications system 200.

[0070] To maintain mobility management and connectivity, the core network portion 102 may also include a mobility management entity (MME) (not shown for simplicity) that manages one or more enhanced packet service (EPS) connections with communication devices 208 operating in the communication system based on user information stored in a home subscriber server (HSS). Other network components in the core network (not shown for simplicity) may include a policy charging and resource function (PCRF) and a packet data network gateway (PDN-GW) that provides connectivity from the core network portion 102 to external packet data networks (e.g., the Internet).

[0071] The core network portion 102 may additionally or alternatively include one or more 5G core (5GC) network entities that collectively perform the functions of the 5GC network. The functions performed by the entities of the 5GC network may roughly correspond to the functions of the S-GW, MME, PCRF, PDN-GW, and HSS of the enhanced packet core (EPC) as described above.

[0072] in addition, Figure 3 A second non-terrestrial network portion 309 is shown coupled to the second base station 111 via a wireless communication link 214. The second non-terrestrial network portion 309 and the second base station 111 may be substantially the same as the first non-terrestrial network portion 308 and the first base station 101.

[0073] A second cell 212 is shown, corresponding to the coverage area provided by the second non-terrestrial network portion 309 .

[0074] Figure 3 The operation of the various elements of the wireless telecommunications system 200 shown in FIG. 2 may be substantially conventional except as modified to provide functionality in accordance with embodiments of the present disclosure discussed herein.

[0075] Figure 4 Movement of the first non-terrestrial network portion 308 (indicated by arrow 506) is shown, resulting in corresponding movement of the first cell 202 indicated by arrow 502. At the same time, the communication device 208 may move, as indicated by arrow 504. Arrows 502, 504, 506 represent movement relative to the surface of the earth; for example, with reference to latitude and longitude. As described above, in some embodiments, the first non-terrestrial network portion 308 may have an earth orbit that is substantially geostationary, such that even though the first non-terrestrial network portion 308 may move relative to the surface of the earth (e.g., around a nominal position), the cell 202 does not substantially move relative to the surface of the earth.

[0076] The communication device 208 may be stationary (relative to the surface of the earth) or mobile.

[0077] As a result of movement of one or both of the cell 202 and the communication device 208 , movement of the communication device 208 relative to the cell 202 may occur, as indicated by arrow 508 .

[0078] Figure 5 A combined process flow diagram and message sequence chart is shown in accordance with an embodiment of the present technology.

[0079] exist Figure 5 , transmissions between the communication device 208 and the first base station 101 and the second base station 111 are shown; it should be understood that these transmissions can be respectively transmitted via the first non-terrestrial network portion 308 and the second non-terrestrial network portion 309. For the sake of clarity, Figure 5 The first non-terrestrial network portion 308 and the second non-terrestrial network portion 309 are not shown.

[0080] Similarly, messages sent between the first base station 101 and the second base station 111 are shown as being sent directly between the base stations. However, in practice, these messages may pass through the core network portion 102.

[0081] One or more steps may involve the transmission of messages having a core network entity (not shown for clarity) as its destination or source. These messages may be received and sent by the first base station 101 or the second base station 111, wherein part or all of the content of the message is passed transparently (i.e., not parsed or evaluated) by the first base station 101 or the second base station 111.

[0082] Initially, the communication device 208 is in an idle mode (eg, RRC Idle) or an inactive mode (eg, RRC Inactive) in the cell 202 .

[0083] Figure 5 The illustrated process begins at step S602, where the communication device 208 determines that it will enter a connected mode, such as an RRC connected mode. The determination may be in response to receiving a paging message or trigger from a non-access stratum (NAS) portion of the communication device 208. The trigger from the NAS portion of the communication device 208 may indicate a request for a specific service setup from the core network portion 102. The trigger and / or request may include an initial user equipment (UE) message for transmission to the core network portion 102.

[0084] In response to the determination of step S602, then at step S604, the communication device 208 initiates a process of establishing or resuming an RRC connection.

[0085] For example, in response to the determination of step S602, then at step S604, if the communication device 208 is in idle mode, the communication device 208 may initiate an RRC connection establishment procedure.

[0086] If the communication device 208 is initially in the inactive mode, then in response to the determination of step S602 , the communication device 208 may initiate an RRC connection recovery procedure at step S604 by, for example, sending an RRC connection recovery request message to the base station 101 .

[0087] As part of step S604 , the communication device 208 may send an initial UE message to the base station 101 .

[0088] Step S604 may be performed according to conventional techniques, for example, including sending an initial random access request including a RACH preamble by the communication device 208 to the base station 101, and forwarding by the first base station 101 from the communication device 208 to the core network part 102 ( Figure 5 (not shown) initial UE message (which may have been received in message 3 of the random access procedure in step S604).

[0089] In some embodiments, step S606 may follow, in which security activation of the communication device 208 is completed. As part of step S606, the communication device 208 may verify the identity of the base station 101 (i.e., authentication), and / or may receive an indication of one or more keys, and / or may receive an indication of one or more inputs for deriving one or more keys that may subsequently be used to verify the integrity of messages received from the base station 101. The one or more keys may additionally be used to encrypt or decrypt information sent to or received from the base station 101.

[0090] In some embodiments, the next step may be step S608, in which the first base station 101 determines the position of the communication device 208. In step S608, the first base station 101 may send measurement configuration information to the communication device 208 to request the communication device 208 to report one or more of its position, speed, direction and measurement results.

[0091] Thus, in response (or in any case), the communication device 208 may report one or more of its position, speed, and direction. Alternatively or additionally, the communication device 208 may report measurements of signals transmitted in the serving cell 202 and / or measurements of signals transmitted in other cells such as the second cell 212.

[0092] In some embodiments, the determination of the cell change time (described below) is subject to the change in cell coverage produced by the spot beams of the first non-terrestrial network portion 308 and the second non-terrestrial network portion 309 due to movement of the corresponding non-terrestrial network portions. In such an embodiment, the communication device 208 may only report its location (and not its speed or direction).

[0093] In step S610, the first base station 101 determines the next cell of the communication device 208, i.e., the cell that the communication device 208 should select as its serving cell next. In a conventional handover procedure, the determination of the next serving cell may be performed immediately before the change of serving cell; that is, there is substantially no delay between the steps of determining the next cell and performing the handover procedure; in fact, the step of determining the next cell may be an integral step within the handover procedure. The handover procedure may be initiated, for example, based on a measurement report, based on a determination that the need for the communication device 208 to change cells is imminent.

[0094] However, in embodiments of the present technology, selection of the next cell may be in response to the communication device 208 entering (or requesting to enter) connected mode, regardless of whether there is an urgent need to change cells.

[0095] exist Figure 5 In the example, the determined next cell is the second cell 212.

[0096] Preferably, in step S610, the first base station 101 also determines the time of the cell change, or the time window in which the cell change will occur. This may be based on the determined position, speed and direction of the communication device 208. In the case where one or both of the first non-terrestrial network portion 308 and the second non-terrestrial network portion 309 are not in geostationary orbit, preferably, the time or time window may be based on the change in the coverage area of ​​the first cell 202 and / or the second cell 212 over time.

[0097] The change in the coverage area of ​​a cell over time may be determined based on the location, orbital speed and direction of the non-terrestrial network portion whose transmissions generate the cell.

[0098] For example, the first base station 101 can determine that the communication device 208 will enter the overlapping area of ​​the first cell 202 and the second cell 212 (i.e., the area where services can be obtained from the first non-terrestrial network part 308 in the first cell 202 or from the second non-terrestrial network part 309 in the second cell 212) after t1 seconds based on the predicted path of the communication device 208 and the future coverage areas of the first cell 202 and the second cell 212.

[0099] The first base station 101 can also determine that the communication device 208 will leave the first cell 202 after t2 seconds. Therefore, the first base station 101 can determine that the time window for the cell change starts at t1 seconds and closes at t2 seconds (that is, the duration of the window is (t2-t1) seconds). In a message indicating a time or a time window, the start and / or end of the time or time window can be indicated in an absolute time (e.g., based on Coordinated Universal Time (UTC)) or relative to the transmission time of the corresponding message. The time window can be characterized by a start time and an end time, or a start time and a duration, or any other appropriate representation. The time period (used to indicate the duration of the time window, or the duration until a time is reached) can be indicated as the number of subframes, frames, time slots or micro time slots or (if semi-persistent scheduling (SPS) is configured) the number of SPS allocations. The time can be indicated based on the frame number.

[0100] In some embodiments, for example, in the case where the first non-terrestrial network portion 308 and the second non-terrestrial network portion 309 are in geostationary orbit, the determination of the time (or time window) for the next cell and cell change may be determined based on the (substantially unchanged) coverage area of ​​the cells 202, 212 and the current position, speed and direction of the communication device 208, as determined in step S608.

[0101] In step S612 , the first base station 101 initiates a handover preparation process, in which the first base station 101 sends a handover request to the base station controlling the selected next cell to provide resources before the cell change (ie, handover) of the communication device 208 .

[0102] exist Figure 5 In the example of , the next cell is the second cell 212 , and therefore, the base station controlling the selected next cell is the second base station 111 .

[0103] The handover request may include one or more of an indication of an identification of the selected next cell (i.e., the second cell 212), an indication of an identification of the communication device 208, an indication of a cell change time or a cell change time window, and a context associated with the communication device 208. The context may include security key information, identification, capabilities of the communication device 208, and the like.

[0104] In response to receiving the handover request, the second base station 111 may send a handover response message to the first base station 101. The handover response message may include an indication of a reserved RACH preamble to be used by the communication device 208 as part of the cell change procedure.

[0105] In some embodiments, no RACH transmission is required as part of the cell change procedure and the RACH preamble is not retained.

[0106] In some embodiments, the second base station 111 determines new security parameters to be used in the next cell selected and includes these parameters in the handover response.

[0107] In some embodiments, the second base station 111 may determine a modified cell change time or cell change time window. For example, it may determine that there is no RACH preamble available for reservation during the entire time window proposed by the first base station 101. Therefore, the second base station 101 may select a RACH preamble that can be used to reserve a portion of the proposed time window, and may indicate the selected RACH preamble and / or the modified time window (which may correspond to a portion or a subset of the proposed time window).

[0108] In step S614, the first base station 101 sends a reconfiguration message to the communication device 208. The reconfiguration message may include one or more of the following:

[0109] - an indication of configuration parameters associated with the service requested by the NAS part of the communication device 208;

[0110] - an indication of the identity of the selected second serving cell 212;

[0111] - an indication of the RACH preamble selected by the second base station 111 and indicated in the handover response message;

[0112] - a cell change time or a cell change time window (as modified by the second base station 111, if applicable);

[0113] New security parameters for the selected second serving cell 212 .

[0114] In particular, in some embodiments, the reconfiguration message includes both an indication of configuration parameters associated with the service requested by the NAS portion of the communication device 208 and an indication of the identity of the selected second serving cell 212 .

[0115] The selected second serving cell 212 may be identified by one or more of a physical cell, a carrier frequency, and a scrambling code, or by any other identifier related to the radio access technology under which the second cell 212 operates.

[0116] Configuration parameters associated with a service requested by the NAS portion of the communication device 208 may include parameters associated with one or more bearers to be established to provide the service.

[0117] The reconfiguration message may be an RRC reconfiguration message (eg, if the communication device 208 was initially in RRC idle mode). Alternatively, the reconfiguration message may be an RRC connection resume message.

[0118] After step S614, the communication device 208 can determine its next serving cell and the time (or time window) at which it should select the next serving cell as its serving cell.The communication device 208 can also determine the RACH preamble to be used as part of the process of selecting the next serving cell.

[0119] Similarly, after step S612, the second base station 111 reserves the RACH preamble code for use by the communication device 208 when performing a cell change procedure to the next serving cell within the time or time window.

[0120] Therefore, unlike the conventional cell change process (whether handover or cell reselection), the details of the cell change (time, identity of the next cell, etc.) are determined before and independently of the time when the cell change is to occur. By decoupling the cell change preparation phase from the cell change, the signaling peaks (whether on the radio access interface or on the interface of the connected base station) caused by a large number of communication devices needing to change cells within the same short time window can be reduced or avoided.

[0121] Thus, as indicated by the break in the timeline, the next step S616 of the process occurs after, but independently of, the timing of the steps described thus far.

[0122] In step S616, the communication device 208 determines that the current time is equal to or falls within the time or time window indicated in the reconfiguration, and therefore a cell change is now required. In response to this determination, the communication device 208 initiates the cell change procedure of step S618 for the second cell 212.

[0123] Therefore, at step S618, the communications device enters RRC connected mode in the second cell 212. Step S618 may comprise conventional procedures for changing cells, such as handover or cell reselection, followed by RRC connection establishment.

[0124] The cell change process of step S618 may include retuning the receiver portion of the transceiver 208a to the carrier frequency associated with the second cell 212 and a synchronization process, in which signals on the carrier frequency associated with the second cell 212 are received and processed to detect synchronization signals, such as a primary synchronization sequence and a secondary synchronization sequence. If the communication device 208 cannot detect a synchronization signal corresponding to the indicated identity of the second cell 212, the communication device 208 may repeat the synchronization process.

[0125] exist Figure 5In the example of , the cell change procedure of step S618 includes transmitting the preamble identified in the reconfiguration message on the RACH of the second cell at step S620. The second base station 111 can use the RACH preamble selected at step S612 and / or the RACH preamble at the time (or time window) determined at step S612 to determine the identity of the communication device 208 based on the transmission at step S618.

[0126] During or after step S618, the communication device 208 may transmit data or control information to the second base station 111. In some embodiments, if new security parameters (eg, security keys) are included in the reconfiguration message, these parameters are used for such data or control information transmission.

[0127] exist Figure 5 In the example shown and described above, the first base station 101 determines the next serving cell, ie the cell that the communication device 208 is to select as its next in-sequence serving cell after the cell controlled by the first base station 101 (the first cell 202 ).

[0128] In some embodiments of the present technology, a sequence of two or more future serving cells and (optionally) corresponding cell change times or time windows may be determined, and a selection step (roughly corresponding to step S610) and a preparation phase (roughly corresponding to step S612 described above) may be performed (e.g., sequentially or substantially simultaneously) for each of the selected cells.

[0129] After the preparation phase for each selected cell has been completed, the reconfiguration message sent at step S614 may include one or more of the following for each selected cell:

[0130] - an indication of the configuration parameters associated with the requested service

[0131] - an indication of the identity of the selected cell;

[0132] - an indication of the RACH preamble used for the selected cell;

[0133] - Setting the selected cell as the cell change time or cell change time window of the serving cell;

[0134] - Security parameters.

[0135] In some embodiments, each of the selected cells is determined by the first base station 101; therefore, steps S616 and S618 may be initiated by the first base station 101 and repeated in sequence for each selected cell.

[0136] In some embodiments, each of the selected cells is determined by the base station responsible for the previous cell in the sequence. Figure 5 As shown, the first selected cell is selected by the first base station 101 .

[0137] In some embodiments, each of the selected cells is determined by the base station responsible for the previous cell in the sequence. Figure 5 As shown, the first selected cell is selected by the first base station 101. Subsequently, the second selected cell is selected by the second base station 111 (because it is the controlling base station of the first selected cell). Therefore, the base station controlling the second selected cell may select the third selected cell. Therefore, steps S616 and S618 may be repeated in sequence for each selected cell, initiated by the respective controlling base station of the cell in the sequence of cells, starting with the current serving cell 202, and continuing with each successive selected cell. When not initiated by the first base station 101, the result of each instance of step S612 may be relayed by the second base station 111 to the first base station 101, and, where applicable, by subsequent base stations to the first base station 101. By such relaying, the first base station 101 may thus receive information about the future cell transmission sequence to be sent to the communication device 208, even in the absence of a direct connection between the first base station 101 and one or more controlling base stations of the second or subsequent selected cells.

[0138] Because the communication device 208 receives information about multiple future cell changes in the reconfiguration message sent in step S614, the amount of signaling can be reduced. In particular, when the communication device 208 is in the previous serving cell, signaling related to the cell change does not need to occur in the cell where the next serving cell has been determined and indicated to the communication device 208.

[0139] In step S612, the handover request message may be modified accordingly to indicate to the second base station 111 that not only the second cell 212 has been selected as the next serving cell for the communication device 208, but also that another cell has been selected as a subsequent serving cell. The handover request message may indicate an identity of the other cell.

[0140] In response to receiving such a handover request, the second base station 111 may avoid determining a cell as a subsequent serving cell for the communication device 208. In some embodiments, if the second base station 111 determines that another cell identified in the handover request in step S612 is appropriate, for example based on a measurement report, a position / speed / direction report received from the communication device 208, the second base station 111 may avoid performing any cell change procedure (e.g., a preparation phase, or sending an identity of another cell to the communication device 208).

[0141] The number of future cells selected may be determined by the first base station 101 based on one or more of the expected duration of a data transmission session or call, the required handover reliability, and the number of users in the geographical area.

[0142] For example, where the expected duration of a data transfer session or call is relatively short, such that the communication device 208 is likely to leave the connected mode while in the next selected cell, the first base station 101 may avoid selecting more than one next cell.

[0143] Because the trajectory of the communication device 208 may change over time, the probability of selecting an inappropriate next cell or time / time window for a cell change increases as the number of future selected cells increases; therefore, in the case where the required handover reliability is high, the first base station 111 may select a smaller number of next cells than in the case where the required handover reliability is low. For example, in the case where the required reliability exceeds a predetermined threshold, the first base station 111 may select only one next cell.

[0144] Therefore, compared with conventional techniques, embodiments of the present technology can reduce the amount of signals associated with the cell change process, thereby mitigating the impact of a large number of communication devices located in a small area, and (collectively) performing cell changes at a high frequency. In particular, when the number of users in a geographic area is high (e.g., higher than a predetermined threshold), the first base station 111 can select a larger number of next cells than when the number of users in the geographic area is lower than the threshold.

[0145] exist Figure 5 In the example of , the selected next cell (second cell 212) and the current serving cell (first cell 202) are generated by spot beams transmitted by different non-terrestrial network parts and controlled by different base stations. In some embodiments, the current serving cell and the selected next cell may be generated by spot beams transmitted by the same non-terrestrial network part and / or controlled by the same base station.

[0146] In the case that the current serving cell and the selected next cell are controlled by the same base station, step S612 may include determining, by the controlling base station, the reserved RACF1 preamble code and / or time / time window.

[0147] In some embodiments, the cell change procedure of step S618 does not require the transmission of the RACF1 preamble. In such embodiments, instead, the handover response (of step S612) and the reconfiguration message (of step S614) may indicate the communication resources allocated by the communication device 208 for one or more transmissions in the next selected cell.

[0148] Additionally or alternatively, other configuration parameters (e.g., parameters related to unlicensed operation) applicable to communications (uplink, downlink, or both) in the next selected cell may be included in the handover response (step S612) and the reconfiguration message (step S614).

[0149] In some embodiments of the present technology, the mobility procedure for change of serving cell may provide service continuity at the radio access network level by preparing a "target" base station associated with the next serving cell prior to the cell change.

[0150] In some embodiments, continuity of service is provided only at the core network (NAS) level.Thus, in some embodiments, the target base station (eg, the second base station 111 ) is not notified in advance of the cell change to be performed by the communication device 208 .

[0151] For example, in some such embodiments, the first (serving) base station 101 may inform the communication device 208 of the identity of the next cell (e.g., the second cell 212) by a message indicating that the current RRC connection will be released. Thus, when the communication device 208 selects the second cell 212 as its serving cell, the communication device 208 may terminate the RRC connection. Service continuity at the NAS / core network level may be provided by a NAS resumption procedure performed after establishing a new RRC connection in the second cell 212.

[0152] By using the connection release message, the need for a handover preparation phase can thus be avoided, so that, for example, Figure 5 Step S612.

[0153] exist Figure 5 In the example of , both the first cell 202 and the second cell 212 are generated by spot beams transmitted by respective non-terrestrial network portions 308, 309, and both operate according to a common radio access technology. In some embodiments, one or both of the first cell 202 and the second cell 212 may be generated by spot beams transmitted by the same non-terrestrial network portion (e.g., the first non-terrestrial network portion 308).

[0154] In some embodiments, instead, one or both of the first cell 202 and the second cell 212 may be generated by infrastructure equipment operating according to different radio access technologies, and / or one or both may be generated by ground infrastructure equipment (e.g., including ground-based base stations). For example, the first cell 202 may be generated by a spot beam operating according to a 5G radio access technology and transmitted by the first non-terrestrial network portion 308, and the second cell 212 may be generated by ground infrastructure equipment operating according to one or more of a 2G, 3G, or 4G radio access technology (e.g., a Global System for Mobile Communications (GSM), a Universal Mobile Telecommunications System (UMTS), or a Long Term Evolution (LTE) technology according to relevant standards).

[0155] Thus, the reconfiguration message or RRC connection release message may indicate an identity of a cell (e.g., including an indication of a carrier frequency) that differs from the current serving cell in certain respects relating to whether the cell is terrestrial or non-terrestrial (and if non-terrestrial, the type of satellite, e.g., geostationary or non-geostationary), and the radio access technology used in the cell. For example, in some embodiments, an RRC connection release message sent to a communication device 208 in a first cell 202 (where the first cell 202 is a non-terrestrial cell, i.e., generated by transmissions of a spot beam such as a non-terrestrial network portion) may indicate a carrier frequency associated with another non-terrestrial cell, or a carrier frequency associated with a terrestrial cell such as an LTE or UMTS cell, which is generated by transmissions of a ground-based base station and does not include a non-terrestrial network portion.

[0156] exist Figure 3 In the example shown, both the first base station 101 and the second base station 111 are shown as being connected to the same core network portion 102. However, in some embodiments (and in particular where the radio access technologies of the first cell 202 and the second cell 212 are different), each of the first base station 101 and the second base station 111 may be connected to a different core network portion. In such embodiments, communication (such as the handover preparation step S612) may require that messages pass through the two core network portions via a link between the respective core network portions.

[0157] Thus, a method for infrastructure equipment of a wireless communication network has been described, the method comprising: receiving a request to enter a connected mode from a communication device in a first cell; and in response to receiving the request, selecting a second cell as a next serving cell for the communication device and sending an indication of an identification of the second cell to the communication device.

[0158] It should be understood that, although in order to provide specific examples, the present disclosure in some aspects focuses on implementations in LTE and / or 5G networks, the same principles can be applied to other wireless telecommunication systems. Therefore, even though the terminology used herein is generally the same or similar to that of the LTE and 5G standards, the present teachings are not limited to current versions of LTE and 5G, and can be equally applied to any suitable arrangement that is not based on LTE or 5G and / or is compatible with any other future versions of LTE, 5G or other standards.

[0159] It may be noted that the various exemplary methods discussed herein may rely on information that is predetermined / predefined in the sense that is known to both the base station and the communication device. It should be understood that such predetermined / predefined information may generally be established, for example, by definition, in the operating standard of the wireless telecommunication system, or in a signal previously exchanged between the base station and the communication device, such as in a system information signal, or associated with a radio resource control establishment signal, or in information stored in a SIM application. That is, the specific manner in which relevant predefined information is established and shared between the various elements of the wireless telecommunication system is not of primary significance to the operating principles described herein. It may also be noted that the various exemplary methods discussed herein rely on information exchanged / transmitted between the various elements of the wireless telecommunication system, and it should be understood that, unless the context otherwise requires, such communication may generally be carried out according to conventional techniques, such as in terms of a specific signal protocol and the type of communication channel used. That is, the specific manner in which relevant information is exchanged between the various elements of the wireless telecommunication system is not of primary significance to the operating principles described herein.

[0160] It should be understood that the principles described herein are not only applicable to certain types of communication devices, but can be more generally applied to any type of communication device or terminal device. For example, the method is not limited to machine-type communication devices / IoT devices or other narrowband communication devices, but can be more generally applied to any type of communication device that operates, for example, using a wireless link to a communication network.

[0161] It should also be understood that the principles described herein are applicable not only to LTE-based wireless telecommunication systems, but also to any type of wireless telecommunication system or system that supports mobility between cells generated by non-terrestrial network parts and cells generated by terrestrial base stations.

[0162] Further particular and preferred aspects of the invention are set out in the accompanying independent and dependent claims. It will be appreciated that features of the dependent claims may be combined with features of the independent claims in ways other than those explicitly set out in the claims.

[0163] Therefore, the foregoing discussion only discloses and describes exemplary embodiments of the present invention. As will be appreciated by those skilled in the art, the present invention may be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the disclosure of the present invention is intended to be illustrative, not limiting, of the scope of the present invention and other claims. The disclosure of any readily identifiable variants of the teachings herein partially defines the scope of the aforementioned claim terms so that no inventive subject matter is dedicated to the public.

[0164] Various features of the present disclosure are defined by the following numbered paragraphs:

[0165] Paragraph 1. A method for infrastructure equipment of a wireless communication network, the method comprising: receiving a request to enter a connection mode from a communication device in a first cell; and in response to receiving the request, selecting a second cell as a next serving cell for the communication device, and sending an indication of an identifier of the second cell to the communication device.

[0166] Paragraph 2. A method according to paragraph 1, comprising: sending parameters associated with one or more bearers to be established for the communication device together with an indication of the identity of the second cell.

[0167] Paragraph 3. The method according to paragraph 1 or paragraph 2 includes: in response to receiving a request, determining a cell change time or a cell change time window for the communication device to select a second cell as its service cell; and sending an indication of the cell change time or the cell change time window together with an indication of the identifier of the second cell.

[0168] Paragraph 4. A method according to any one of paragraphs 1 to 3, the method comprising: determining a location of the communication device, wherein the second cell is selected based on the determined location.

[0169] Paragraph 5. According to a method described in any one of paragraphs 1 to 4, the method includes: in response to receiving the request, selecting a third cell as the service cell of the communication device, the third cell becoming the service cell of the communication device after the second cell, and sending an indication of the identity of the third cell to the communication device together with an indication of the identity of the second cell.

[0170] Paragraph 6 A method according to any one of paragraphs 1 to 5, wherein the first cell is generated by a spot beam of a non-terrestrial network portion, the spot beam of the non-terrestrial network portion forming an area within which radio signals can be sent to and received by the non-terrestrial network portion, or radio signals can be sent from the non-terrestrial network portion and received within the area formed by the spot beam.

[0171] Paragraph 7. A method according to paragraph 6, wherein the non-terrestrial network portion is in a non-geostationary Earth orbit.

[0172] Paragraph 8. A method according to paragraph 6 or paragraph 7, wherein the coverage area of ​​the first cell moves relative to the surface of the earth.

[0173] Paragraph 9. A method according to any of paragraphs 1 to 8, wherein the indication of the identity of the second cell is sent within a radio resource control, RRC, reconfiguration message.

[0174] Paragraph 10. A method according to any of paragraphs 1 to 9, wherein the request to enter connected mode comprises a request to establish an RRC connection.

[0175] Paragraph 11. A method according to any of paragraphs 1 to 9, wherein the request to enter connected mode includes a request to resume an RRC connection.

[0176] Paragraph 12. A method for a communication device in a wireless communication network, the method comprising: sending a request to enter a connection mode to an infrastructure device of the wireless communication network in a first cell; and receiving an indication of the identity of a second cell that will become the next service cell of the communication device, the indication of the identity of the second cell being sent by the infrastructure device in response to receiving the request.

[0177] Paragraph 13. A method as described in paragraph 12, comprising receiving, together with an indication of an identity of the second cell, parameters associated with one or more bearers to be established for the communications device.

[0178] Paragraph 14. A method as described in paragraph 12 or paragraph 13, the method comprising: receiving, together with an indication of the identity of the second cell, an indication of a cell change time or cell change time window at which the communications device will select the second cell as its serving cell.

[0179] Paragraph 15. A method as described in any of paragraphs 12 to 14, comprising determining a location of the communications device and sending an indication of the determined location to the infrastructure equipment before receiving the indication of the identity of the second cell.

[0180] Paragraph 16. A method according to any one of paragraphs 12 to 15, the method comprising: receiving, from the infrastructure equipment, an indication of the identification of a third cell which will become the serving cell for the communication device, together with an indication of the identification of the second cell, the third cell becoming the serving cell for the communication device after the second cell.

[0181] Paragraph 17. A method according to any of paragraphs 12 to 16, wherein the first cell is generated by a spot beam of the non-terrestrial network portion.

[0182] Paragraph 18. The method of paragraph 17, wherein the non-terrestrial network portion is in a non-geostationary Earth orbit.

[0183] Paragraph 19. A method according to paragraph 17 or paragraph 18, wherein the coverage area of ​​the first cell moves relative to the surface of the earth.

[0184] Paragraph 20. A method according to any of paragraphs 12 to 19, wherein the indication of the identity of the second cell is sent within a radio resource control, RRC, reconfiguration message.

[0185] Paragraph 21. A method according to any of paragraphs 12 to 20, wherein the request to enter connected mode includes a request to establish an RRC connection.

[0186] Paragraph 22. A method according to any of paragraphs 12 to 20, wherein the request to enter connected mode includes a request to resume an RRC connection.

[0187] Paragraph 23. A method for infrastructure equipment of a wireless communication network, the method comprising: selecting a second cell generated by a non-terrestrial network portion as a next serving cell for a communication device having a connection with the infrastructure equipment, and sending a message indicating that the connection is to be released, the message including an indication of an identity of the second cell.

[0188] Paragraph 24. A method as described in paragraph 23, wherein the connection to the infrastructure equipment is in a cell created by the non-terrestrial network portion.

[0189] Paragraph 25. The method of Paragraph 23, wherein the infrastructure equipment is ground infrastructure equipment.

[0190] Paragraph 26. A method for a communication device having a connection with infrastructure equipment of a wireless communication network, the method comprising: receiving a message from the infrastructure equipment indicating that the connection is to be released, the message including an indication of an identification of a second cell that is to be the next serving cell for the communication device, the second cell being generated by a non-terrestrial network portion.

[0191] Paragraph 27. A method as described in paragraph 26, wherein the connection to the infrastructure equipment is in a cell created by the non-terrestrial network portion.

[0192] Paragraph 28. The method of Paragraph 26, wherein the infrastructure equipment is ground infrastructure equipment.

[0193] Paragraph 29. Infrastructure equipment of a wireless communication network, the wireless communication network including a non-terrestrial network portion, wherein the infrastructure equipment includes a controller circuit and a transceiver circuit, and the controller circuit and the transceiver circuit are configured so that the infrastructure equipment is operable to: receive a request to enter a connected mode from a communication device in a first cell; and in response to receiving the request, select a second cell as a next serving cell for the communication device and send an indication of an identification of the second cell to the communication device.

[0194] Paragraph 30. An integrated circuit for infrastructure equipment of a wireless communication network, the wireless communication network including a non-terrestrial network portion, wherein the integrated circuit includes a controller circuit and a transceiver circuit, the controller circuit and the transceiver circuit being configured to operate together so that the infrastructure equipment is operable to: receive a request to enter a connected mode from a communication device in a first cell; and in response to receiving the request, select a second cell as a next serving cell for the communication device and send an indication of an identification of the second cell to the communication device.

[0195] Paragraph 31. Infrastructure equipment of a wireless communication network, the wireless communication network including a non-terrestrial network portion, wherein the infrastructure equipment includes a controller circuit and a transceiver circuit, the controller circuit and the transceiver circuit being configured such that the infrastructure equipment is operable to: select a second cell generated by the non-terrestrial network portion as a next serving cell for a communication device having a connection with the infrastructure equipment, and send a message indicating that the connection is to be released, the message including an indication of an identity of the second cell.

[0196] Paragraph 32. An integrated circuit for infrastructure equipment of a wireless communication network, the wireless communication network including a non-terrestrial network portion, wherein the integrated circuit includes a controller circuit and a transceiver circuit, the controller circuit and the transceiver circuit being configured to operate together so that the infrastructure equipment is operable to: select a second cell generated by the non-terrestrial network portion as a next serving cell for a communication device having a connection with the infrastructure equipment, and send a message indicating that the connection is to be released, the message including an indication of an identity of the second cell.

[0197] Paragraph 33. A communication device for use in a wireless communication network, wherein the communication device includes a controller circuit and a transceiver circuit, and the controller circuit and the transceiver circuit are configured to enable the communication device to: send a request to enter a connection mode to an infrastructure device of the wireless communication network in a first cell; and receive an indication of the identity of a second cell as a next service cell for the communication device, the indication of the identity of the second cell being sent by the infrastructure device in response to receiving the request.

[0198] Paragraph 34. An integrated circuit for a communication device for use in a wireless communication network, wherein the integrated circuit includes a controller circuit and a transceiver circuit, and the controller circuit and the transceiver circuit are configured to operate together so that the communication device is operable to: send a request to enter a connected mode to an infrastructure device in a first cell; and receive an indication of an identification of a second cell as a next serving cell for the communication device, the indication of the identification of the second cell being sent by the infrastructure device in response to receiving the request.

[0199] Paragraph 35. A communication device for use in a wireless communication network, wherein the communication device includes a controller circuit and a transceiver circuit, and the controller circuit and the transceiver circuit are configured so that when the communication device has a connection with infrastructure equipment of the wireless communication network, the communication device is operable to receive a message from the infrastructure equipment indicating that the connection is to be released, the message including an indication of an identification of a second cell that will be the next serving cell for the communication device, the second cell being generated by a non-terrestrial network portion.

[0200] Paragraph 36. An integrated circuit for a communication device for use in a wireless communication network, wherein the integrated circuit includes a controller circuit and a transceiver circuit, and the controller circuit and the transceiver circuit are configured to operate together so that when the communication device has a connection with infrastructure equipment of the wireless communication network, the communication device is operable to: receive a message from the infrastructure equipment indicating that the connection is to be released, the message including an indication of an identification of a second cell to be a next serving cell for the communication device, the second cell being generated by a non-terrestrial network portion.

[0201] Further particular and preferred aspects of the invention are set out in the accompanying independent and dependent claims. It will be appreciated that features of the dependent claims may be combined with features of the independent claims in ways other than those explicitly set out in the claims.

[0202] References

[0203] [1] 3GPP TR 38.811 "Study on New Radio (NR) to support non terrestrialnetworks (Release 15)", December 2017

[0204] [2] Holma H. ​​and Toskala A, "LTE for UMTS OFDMA and SC-FDMA basedradio access", John Wiley and Sons, 2009.

Claims

1. A method for infrastructure equipment of a wireless communication network, the method comprising: receiving a request to enter a connected mode from a communication device in a first cell, the first cell being generated by a spot beam of a non-terrestrial network portion; and in response to receiving the request, independently of the time at which the cell change is to occur, selecting a second cell as the next serving cell for the communication device, and determining a cell change time or a cell change time window at which the communication device is to select the second cell as its serving cell, and A radio resource control, RRC, reconfiguration message or an RRC connection restoration message is sent to the communications device, comprising an indication of the identity of the second cell and an indication of the cell change time or the cell change time window.

2. The method according to claim 1, comprising: Parameters associated with one or more bearers to be established for the communications device are sent along with the indication of the identity of the second cell.

3. The method according to claim 1, comprising: determining a location of the communication device, wherein: The second cell is selected based on the determined location.

4. The method according to claim 1, comprising: In response to receiving the request, A third cell is selected as the serving cell of the communication device, the third cell will become the serving cell of the communication device after the second cell, and an indication of the identity of the third cell is sent to the communication device together with an indication of the identity of the second cell.

5. The method according to claim 1, wherein: The spot beam of the non-terrestrial network portion forms an area within which radio signals can be transmitted to and received by the non-terrestrial network portion, or the radio signals can be transmitted from the non-terrestrial network portion and received within the area formed by the spot beam.

6. The method according to claim 5, wherein: The non-terrestrial network portion is in a non-geostationary Earth orbit.

7. The method according to claim 5, wherein: The coverage area of ​​the first cell moves relative to the surface of the earth.

8. The method according to claim 1, wherein: The request to enter the connected mode comprises a request to establish an RRC connection.

9. The method according to claim 1, wherein: The request to enter the connected mode comprises a request to resume the RRC connection.

10. A method for a communication device in a wireless communication network, the method comprising: sending a request to enter a connected mode to an infrastructure device of the wireless communication network in a first cell, the first cell being generated by a spot beam of a non-terrestrial network portion; as well as Receiving a Radio Resource Control, RRC, reconfiguration message or an RRC connection resumption message, the RRC reconfiguration message or the RRC connection resumption message comprising an indication of an identity of a second cell which will become a next serving cell for the communication device, and an indication of a cell change time or a cell change time window during which the communication device will select the second cell as its serving cell, the indication of the identity of the second cell and the indication of the cell change time or the cell change time window being sent by the infrastructure equipment in response to receiving the request, independently of the time at which the cell change is to occur.

11. The method according to claim 10, comprising: Parameters associated with one or more bearers to be established for the communications device are received along with an indication of the identity of the second cell.

12. The method according to claim 10, comprising: determining a location of the communication device, and Prior to receiving the indication of the identity of the second cell, an indication of the determined position is sent to the infrastructure equipment.

13. The method according to claim 10, comprising: An indication of the identity of a third cell to become a serving cell for the communications device is received from the infrastructure equipment together with the indication of the identity of the second cell, the third cell to become a serving cell for the communications device after the second cell.

14. The method according to claim 10, wherein: The non-terrestrial network portion is in a non-geostationary Earth orbit.

15. The method according to claim 10, wherein: The coverage area of ​​the first cell moves relative to the surface of the earth.

16. The method according to claim 10, wherein: The request to enter the connected mode comprises a request to establish an RRC connection.

17. The method according to claim 10, wherein: The request to enter the connected mode comprises a request to resume the RRC connection.

18. A method for infrastructure equipment of a wireless communication network, the method comprising: selecting a second cell generated by the non-terrestrial network portion as a next serving cell for a communication device having a connection to the infrastructure device via a first cell independently of the time at which a cell change is to occur, and determining a cell change time or a cell change time window at which the communication device is to select the second cell as its serving cell, the first cell being generated by a spot beam of the non-terrestrial network portion, and A radio resource control (RRC) reconfiguration message or an RRC connection recovery message is sent indicating that the connection is to be released, the RRC reconfiguration message or the RRC connection recovery message including an indication of an identity of the second cell, and an indication of the cell change time or the cell change time window.

19. The method according to claim 18, wherein: The infrastructure equipment is ground infrastructure equipment.

20. A method for a communication device having a connection with infrastructure equipment of a wireless communication network via a first cell, the method comprising: receiving a radio resource control (RRC) reconfiguration message or an RRC connection resume message from the infrastructure equipment indicating that the connection is to be released, the RRC reconfiguration message or the RRC connection resume message comprising an indication of an identity of a second cell to be a next serving cell for the communications device, and an indication of a cell change time or a cell change time window during which the communications device is to select the second cell as its serving cell, the second cell being generated by a non-terrestrial network portion, the first cell being generated by a spot beam of the non-terrestrial network portion, Therein, the infrastructure device selects the second cell as the next serving cell of the communication device independently of the time when the cell change is to occur, and determines the cell change time or the cell change time window.

21. The method according to claim 20, wherein: The infrastructure equipment is ground infrastructure equipment.

22. Infrastructure equipment of a wireless communication network, the wireless communication network comprising a non-terrestrial network portion, wherein: The infrastructure equipment comprises a controller circuit and a transceiver circuit configured such that the infrastructure equipment is operable to: receiving a request to enter a connected mode from a communication device in a first cell, the first cell being generated by a spot beam of a non-terrestrial network portion; and in response to receiving the request, independently of the time at which the cell change is to occur, selecting a second cell as the next serving cell for the communication device, and determining a cell change time or a cell change time window at which the communication device is to select the second cell as its serving cell, and A radio resource control, RRC, reconfiguration message or an RRC connection restoration message is sent to the communications device, comprising an indication of the identity of the second cell and an indication of the cell change time or the cell change time window.

23. An integrated circuit for use in infrastructure equipment of a wireless communication network, the wireless communication network comprising a non-terrestrial network portion, wherein: The integrated circuit includes a controller circuit and a transceiver circuit configured to operate together such that the infrastructure equipment is operable to: receiving a request to enter a connected mode from a communication device in a first cell, the first cell being generated by a spot beam of a non-terrestrial network portion; and in response to receiving the request, independently of the time at which the cell change is to occur, selecting a second cell as the next serving cell for the communication device, and determining a cell change time or a cell change time window at which the communication device is to select the second cell as its serving cell, and A radio resource control, RRC, reconfiguration message or an RRC connection restoration message is sent to the communications device, comprising an indication of the identity of the second cell and an indication of the cell change time or the cell change time window.

24. Infrastructure equipment of a wireless communication network, the wireless communication network comprising a non-terrestrial network portion, wherein: The infrastructure equipment comprises a controller circuit and a transceiver circuit configured such that the infrastructure equipment is operable to: selecting a second cell generated by the non-terrestrial network portion as a next serving cell for a communication device having a connection to the infrastructure device via a first cell independently of the time at which a cell change is to occur, and determining a cell change time or a cell change time window at which the communication device is to select the second cell as its serving cell, the first cell being generated by a spot beam of the non-terrestrial network portion, and A radio resource control (RRC) reconfiguration message or an RRC connection recovery message is sent indicating that the connection is to be released, the RRC reconfiguration message or the RRC connection recovery message including an indication of an identity of the second cell, and an indication of the cell change time or the cell change time window.

25. An integrated circuit for use in infrastructure equipment of a wireless communication network, the wireless communication network comprising a non-terrestrial network portion, wherein: The integrated circuit includes a controller circuit and a transceiver circuit configured to operate together such that the infrastructure equipment is operable to: selecting a second cell generated by the non-terrestrial network portion as a next serving cell for a communication device having a connection to the infrastructure device via a first cell independently of the time at which a cell change is to occur, and determining a cell change time or a cell change time window at which the communication device is to select the second cell as its serving cell, the first cell being generated by a spot beam of the non-terrestrial network portion, and A radio resource control (RRC) reconfiguration message or an RRC connection recovery message is sent indicating that the connection is to be released, the RRC reconfiguration message or the RRC connection recovery message including an indication of an identity of the second cell, and an indication of the cell change time or the cell change time window.

26. A communication device for use in a wireless communication network, wherein: The communication device comprises a controller circuit and a transceiver circuit, the controller circuit and the transceiver circuit being configured such that the communication device is operable to: sending a request to enter a connected mode to an infrastructure device of the wireless communication network in a first cell, the first cell being generated by a spot beam of a non-terrestrial network portion; as well as Receiving a Radio Resource Control, RRC, reconfiguration message or an RRC connection restoration message, the RRC reconfiguration message or the RRC connection restoration message comprising an indication of the identity of a second cell which will become the next serving cell of the communication device, and an indication of a cell change time or a cell change time window during which the communication device will select the second cell as its serving cell, the indication of the identity of the second cell and the indication of the cell change time or the indication of the cell change time window being sent by the infrastructure equipment in response to receiving the request, independently of the time at which the cell change is to occur.

27. An integrated circuit for a communication device for use in a wireless communication network, wherein: The integrated circuit includes a controller circuit and a transceiver circuit, the controller circuit and the transceiver circuit being configured to operate together such that the communication device is operable to: sending a request to enter a connected mode to an infrastructure device in a first cell, the first cell being generated by a spot beam of the non-terrestrial network portion; as well as Receiving a Radio Resource Control, RRC, reconfiguration message or an RRC connection restoration message, the RRC reconfiguration message or the RRC connection restoration message comprising an indication of the identity of a second cell which will become the next serving cell of the communication device, and an indication of a cell change time or a cell change time window during which the communication device will select the second cell as its serving cell, the indication of the identity of the second cell and the indication of the cell change time or the indication of the cell change time window being sent by the infrastructure equipment in response to receiving the request, independently of the time at which the cell change is to occur.

28. A communication device for use in a wireless communication network, wherein: The communication device comprises a controller circuit and a transceiver circuit, the controller circuit and the transceiver circuit being configured such that when the communication device has a connection with infrastructure equipment of the wireless communication network via a first cell, the communication device is operable to: receiving a radio resource control (RRC) reconfiguration message or an RRC connection resume message from the infrastructure equipment indicating that the connection is to be released, the RRC reconfiguration message or the RRC connection resume message comprising an indication of an identity of a second cell to be a next serving cell for the communications device, and an indication of a cell change time or a cell change time window during which the communications device is to select the second cell as its serving cell, the second cell being generated by a non-terrestrial network portion, the first cell being generated by a spot beam of the non-terrestrial network portion, Therein, the infrastructure device selects the second cell as the next serving cell of the communication device independently of the time when the cell change is to occur, and determines the cell change time or the cell change time window.

29. An integrated circuit for a communication device for use in a wireless communication network, wherein: The integrated circuit comprises a controller circuit and a transceiver circuit, the controller circuit and the transceiver circuit being configured to operate together such that when the communication device has a connection with infrastructure equipment of the wireless communication network via a first cell, the communication device is operable to: receiving a radio resource control (RRC) reconfiguration message or an RRC connection resume message from the infrastructure equipment indicating that the connection is to be released, the RRC reconfiguration message or the RRC connection resume message comprising an indication of an identity of a second cell to be a next serving cell for the communications device, and an indication of a cell change time or a cell change time window during which the communications device is to select the second cell as its serving cell, the second cell being generated by a non-terrestrial network portion, the first cell being generated by a spot beam of the non-terrestrial network portion, Therein, the infrastructure device selects the second cell as the next serving cell of the communication device independently of the time when the cell change is to occur, and determines the cell change time or the cell change time window.

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