SIB-based distributed access for satellite handover without L3 mobility

Abstract

A method, an apparatus, and a computer program product are provided. In the context of the method, the method receives a system information block from a first network node via a source satellite, where the system information block indicates a random access channel opportunity window in which a user equipment should access the first network node or a second network node. The method includes determining an access time within a random access channel opportunity window based on a system information block. The method comprises transmitting, at an access time, a random access channel preamble to a first network node or a second network node via a target satellite.

Description

Technical Field

[0001] Example embodiments relate generally to satellite handover without layer 3 mobility, and more particularly to satellite handover based on a random access channel. Background Art

[0002] User equipment devices supporting non-terrestrial networks have global navigation satellite system capabilities. In non-terrestrial network systems, 5G base station (i.e., gNB) functions can be deployed on satellites or deployed elsewhere and relayed by satellites in a transparent manner to provide communication coverage over large areas that cellular networks cannot reach. This function can be used to connect IoT devices around the world and provide personal communications in remote areas and disaster relief.

[0003] Low Earth Orbit satellites orbit about 600-1500 km above the Earth and move at a speed of about 7.5 km / s relative to the Earth. The beam footprint radius of a low Earth orbit satellite is typically between 100 and 1000 km. For Earth-fixed cells, the satellite continuously adjusts the satellite beam pointing direction to fix new radio cells and new radio beams to specific points on the Earth. For Earth-mobile cells, the satellite beam pointing direction is fixed and the beam footprint (i.e., new radio cells) moves on the Earth. In addition, for Earth-mobile cells, mobility is mainly due to satellite movement, because the satellite moves faster than the user equipment devices on the ground.

[0004] For unchanged physical cell identifiers, the serving network node and the cell on the ground do not change after satellite switching. Therefore, most of the cell configuration can be retained without changing the physical cell identifier, frequency, and other cell configuration parameters (e.g., servingCellconfigCommon). In this case, the user equipment does not need to perform third-layer mobility (i.e., switching process), can avoid refreshing the buffer, and does not need to update the security key. In this scenario, non-terrestrial network cells can be deployed as quasi-earth fixed cells because the area of ​​cell coverage should not change. In addition, the network should indicate to the user equipment how and when to resynchronize after satellite switching, and the target satellite information should be provided via broadcast signaling before satellite switching (radio resource control dedicated signaling should not be used to reduce Uu interface overhead).

[0005] In layer 3 mobility, the network can use different features to spread the user equipment access to new cells across time (e.g. blind handover, conditional handover based on location / time, handover without random access channel). This means that by using user equipment-specific radio resource control signaling, the network can use different configuration settings to avoid random access channel storms.

[0006] Unchanged primary cell identifier mobility can be performed with and without the random access channel procedure. Unchanged primary cell identifier mobility is described as a case where the cell identity and most logical parameters associated with the cell are not modified from the user equipment's perspective, but the satellite providing the radio footprint to the cell changes. Physical layer measurements and parameters are modified.

[0007] This type of mobility can be deployed for non-geostationary orbits. Specifically, this can be applicable to low earth orbits where the speed of satellites can be as high as 7000m / s or more. As the satellites "disappear" over the horizon, there is a need to switch to the satellite that provides coverage for a given cell. The concept of a constant primary cell identifier is an example of the above.

[0008] For hard satellite handoff, the inbound satellite does not begin radio transmission or reception until the outbound satellite no longer provides coverage for the cell. For soft handoff, transmission and / or reception provided by both satellites can coexist for a period of time.

[0009] The user equipment eventually detaches from the source satellite during the handover interval and attaches to the inbound satellite.System information broadcasts (or system information blocks) are used to convey important information to user equipment devices for handover.

[0010] For hard satellite handover, since some user equipment devices may not be able to perform mobility without random access channel access, the user equipment may need to transmit or receive via a different satellite (e.g., a target satellite). For soft handover, there may also be user equipment devices that cannot perform mobility without a random access channel.

[0011] In the case of a soft handover, the user equipment may need to use a configured or dynamic uplink grant in the target cell to indicate that the handover has been completed or receive a physical downlink shared channel sent from the target satellite. The physical downlink shared channel may include an uplink allocation to "handshake" with the target satellite to indicate that the handover is complete. However, the user equipment device may not have the ability to monitor both the source and target satellites at the same time. In this case, when the outbound satellite is still being monitored, the user equipment may not be able to receive the physical downlink shared channel sent from the target satellite or obtain the uplink synchronization required through the configured uplink grant because the outbound satellite is still providing coverage and service.

[0012] Given that the signaling for unchanged physical cell identifier mobility is based on system information broadcasts, and given that several user equipment devices may need to rely on unchanged physical cell identifiers based on random access channels, a certain number of user equipment devices may be separated from the source satellite and access a new cell at the same time. This may lead to a random access channel storm. Therefore, a method is needed to extend random access channel access for these user equipment devices without radio resource control signaling. Summary of the invention

[0013] In one or more embodiments, a user equipment (110a / 110b / 110c) is provided, the user equipment comprising at least one processor and at least one memory storing instructions, the instructions, when executed by the processor, causing the user equipment (110a / 110b / 110c) to: receive (805) a system information block (805a) from a first network node (112) via a source satellite, wherein the system information block (805a) indicates a random access channel opportunity window (855), in which the user equipment (110a / 110b / 110c) should access the first network node (112) or a second network node. The user equipment (110a / 110b / 110c) is also caused to: determine an access time (815 / 825 / 840) within the random access channel opportunity window (855) based on the system information block (805a). The user equipment (110a / 110b / 110c) is also caused to send (820 / 830 / 845) a random access channel preamble (820a / 830a / 845a) to the first network node (112) or the second network node via the target satellite at the access time (815 / 825 / 840).

[0014] In one or more embodiments, a network node (112) is provided, the network node comprising at least one processor and at least one memory storing instructions, the instructions, when executed by the processor, causing the network node (112) to: send (805) a system information block (805a) to a user equipment (110a / 110b / 110c) via a source satellite (114), wherein the system information block (805a) indicates a random access channel opportunity window (855) in which the user equipment (110a / 110b / 110c) should access the network node (112) or another network node (115) via a target satellite (116). Additionally or alternatively, the network node (112) may be caused to: receive (820 / 830 / 845) a random access channel preamble (820a / 830a / 845a) from the user equipment (110a / 110b / 110c) via the target satellite (116) at an access time (815 / 825 / 840) within the random access channel opportunity window (855).

[0015] In one or more embodiments, a computer-implemented method performed by a user equipment (110a / 110b / 110c) is provided, the method comprising: receiving (805) a system information block (805a) from a first network node (112) via a source satellite (114), wherein the system information block (805a) indicates a random access channel opportunity window (855) in which the user equipment (110a / 110b / 110c) should access the first network node (112) or a second network node. The method also includes determining an access time (815 / 825 / 840) within the random access channel opportunity window (855) based on the system information block (805a). The method also includes sending (820 / 830 / 845) a random access channel preamble (820a / 830a / 845a) to the first network node (112) or the second network node (115) via the target satellite (116) at an access time (815 / 825 / 840).

[0016] In one or more embodiments, a computer-implemented method performed by a network node (112) is provided, the method comprising: sending (805) a system information block (805a) to a user equipment (110a / 110b / 110c) via a source satellite, wherein the system information block (805a) indicates a random access channel opportunity window (855) during which the user equipment (110a / 110b / 110c) should access the network node (112) or another network node (115) via a target satellite (116). Additionally or alternatively, the method comprises: receiving (820 / 830 / 845) a random access channel preamble (820a / 830a / 845a) from the user equipment (110a / 110b / 110c) via the target satellite at an access time (815 / 825 / 840) within the random access channel opportunity window (855).

[0017] In one or more embodiments, a non-transitory computer-readable storage medium is provided, the medium comprising computer instructions, which when executed by a user equipment (110), causes the user equipment (100) to: receive (805) a system information block (805a) from a first network node (112) via a source satellite, wherein the system information block (805a) indicates a random access channel opportunity window (855) in which the user equipment (110a / 110b / 110c) should access the first network node (112) or a second network node. The user equipment (110a / 110b / 110c) is further caused to: determine an access time (815 / 825 / 840) within the random access channel opportunity window (855) based on the system information block (805a). The user equipment (110a / 110b / 110c) is also caused to send (820 / 830 / 845) a random access channel preamble (820a / 830a / 845a) to the first network node (112) or the second network node via the target satellite at the access time (815 / 825 / 840).

[0018] In one or more embodiments, a non-transitory computer-readable storage medium is provided, the medium comprising computer instructions that, when executed by a network node (112), cause the network node (112) to: send (805) a system information block (805a) to a user equipment (110a / 110b / 110c) via a source satellite, wherein the system information block (805a) indicates a random access channel opportunity window (855) during which the user equipment (110a / 110b / 110c) should access the network node (112) or another network node via a target satellite. Additionally or alternatively, the network node (112) may be caused to: receive (820 / 830 / 845) a random access channel preamble (820a / 830a / 845a) from the user equipment (110a / 110b / 110c) via the target satellite at an access time (815 / 825 / 840) within the random access channel opportunity window (855).

[0019] In one or more embodiments, a user equipment (110a / 110b / 110c) is provided, the user equipment comprising: a component for receiving (805) a system information block (805a) from a first network node (112) via a source satellite, wherein the system information block (805a) indicates a random access channel opportunity window (855) in which the user equipment (110a / 110b / 110c) should access the first network node (112) or a second network node. The user equipment (110a / 110b / 110c) further comprises: a component for determining an access time (815 / 825 / 840) within the random access channel opportunity window (855) based on the system information block (805a). The user equipment (110a / 110b / 110c) further comprises means for sending (820 / 830 / 845) a random access channel preamble (820a / 830a / 845a) to the first network node (112) or the second network node via the target satellite at an access time (815 / 825 / 840).

[0020] In one or more embodiments, a network node (112) is provided, the network node comprising: means for sending (805) a system information block (805a) to a user equipment (110a / 110b / 110c) via a source satellite, wherein the system information block (805a) indicates a random access channel opportunity window (855) during which the user equipment (110a / 110b / 110c) should access the network node (112) or another network node via a target satellite. Additionally or alternatively, the network node (112) comprises: means for receiving (820 / 830 / 845) a random access channel preamble (820a / 830a / 845a) from the user equipment (110a / 110b / 110c) via the target satellite at an access time (815 / 825 / 840) within the random access channel opportunity window (855). BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Having generally described certain example embodiments of the present disclosure, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, in which:

[0022] Figure 1 is a block diagram of a system according to an example embodiment of the present disclosure, the system comprising a user equipment, a network node, a source satellite, and a target satellite configured to communicate via at least uplink and downlink transmissions;

[0023] Figure 2 According to an exemplary embodiment of the present disclosure Figure 1 A block diagram of an example communication system in which the system may be deployed;

[0024] Figure 3 is an example architecture of a non-terrestrial network according to the previous embodiment;

[0025] Figure 4A-4B illustrates a satellite handover scenario according to the previous embodiment where the serving network node does not change;

[0026] Figure 5 is a system information block containing satellite assistance information for non-terrestrial network access according to the aforementioned embodiment;

[0027] Fig. 6A is a media access control element including a fallback indicator according to the aforementioned embodiment;

[0028] Figure 6B is a table of fallback parameter values ​​according to the previous embodiment;

[0029] Figure 7 It illustrates that a user equipment according to an example embodiment of the present disclosure accesses a target satellite at a specific access time;

[0030] Fig. 8A is a flow chart of a system information block based random access with hard satellite handover according to an example embodiment of the present disclosure;

[0031] Figure 8B is a flow chart of a system information block based random access with soft satellite handover according to an example embodiment of the present disclosure;

[0032] Fig. 9 is a system information block indicating a random access channel opportunity window according to an example embodiment of the present disclosure;

[0033] Fig.10 is a flow chart illustrating a process performed by a user equipment in order to transmit a random access channel preamble at an access time according to an example embodiment of the present disclosure; and

[0034] Fig.11 is a flow chart illustrating a process performed by a network node in order to receive a random access channel preamble at an access time according to an example embodiment of the present disclosure. DETAILED DESCRIPTION

[0035] Some embodiments of the present disclosure will be described more fully below with reference to the accompanying drawings, in which some but not all embodiments are shown. In fact, various embodiments may be embodied in many different forms and should not be construed as being limited to the embodiments described herein; on the contrary, these embodiments are provided so that the present disclosure satisfies applicable legal requirements. The same figure numerals always refer to the same elements. As used herein, the terms "data", "content", "information" and similar terms may be used interchangeably to refer to data that can be sent, received and / or stored according to embodiments of the present disclosure. Therefore, the use of any such terms should not be considered to limit the spirit and scope of the embodiments of the present disclosure.

[0036] In addition, as used herein, the term "circuitry" refers to (a) a pure hardware circuit implementation (e.g., an implementation in analog circuitry and / or digital circuitry); (b) a combination of circuitry and (multiple) computer program products, including software and / or firmware instructions stored on one or more computer-readable memories, which work together to cause the device to perform one or more functions described herein; and (c) a circuit, such as (multiple) microprocessors or a portion of (multiple) microprocessors, which requires software or firmware to operate, even if the software or firmware is not physically present. This definition of "circuitry" applies to all uses of the term herein, including in any claims. As another example, as used herein, the term "circuitry" also includes an implementation including one or more processors and / or (multiple) portions thereof and accompanying software and / or firmware. As another example, for example, as used herein, the term "circuitry" also includes a baseband integrated circuit or application processor integrated circuit for a mobile phone, or a similar integrated circuit in a server, cellular network equipment, other network equipment (such as a core network equipment), a field programmable gate array, and / or other computing devices.

[0037] As used herein, the term "computer-readable medium" refers to non-transitory storage hardware, non-transitory storage devices, or non-transitory computer system memory that can be accessed by a controller, a microcontroller, a computing system, or a module of a computing system to encode computer executable instructions or software programs thereon. Non-transitory "computer-readable medium" can be accessed by a computing system or a module of a computing system to retrieve and / or execute computer executable instructions or software programs encoded on the medium. Examples of non-transitory computer-readable media may include, but are not limited to, one or more types of hardware memory, non-transitory tangible media (e.g., one or more magnetic storage disks, one or more optical disks, one or more universal synchronous bus (USB) flash drives), computer system memory, or random access memory, such as dynamic random access memory (DRAM), static random access memory (SRAM), extended data output random access memory (EDO RAM), etc.

[0038] like Figure 1 As shown in FIG. 1 , a system 100 is provided according to an exemplary embodiment to allocate time to perform a handover based on a random access channel. Although the system can be configured in various ways, Figure 1 100, the system includes a user device 110, network nodes 112 and 115, a source satellite 114, and a target satellite 116 configured to communicate via uplink and downlink transmission and reception beams. Although one user device, two network nodes, and two satellites are depicted, in other embodiments, the system may include, and the user device 110, network nodes 112 and 115, source satellite 114, and target satellite 116 may communicate with other user devices, network nodes, and satellites. For example, the target satellite 116 may be connected to a network node different from the network nodes 112 and 115. In one or more embodiments, the user device 110, the network nodes 112 and 115, the source satellite 114, and the target satellite 116 may be configured to support, for example, 5G, advanced 5G, or 6G. In one or more embodiments, the system 100 may support carrier aggregation and / or dual connectivity. As described below, the system may support paging-triggered small data transmissions, such as small data transmissions terminated by a mobile terminal and / or small data transmissions initiated by a mobile terminal.

[0039] The data transmitted via the uplink and downlink beams between user equipment 110, network nodes 112 and 115, source satellite 114, and target satellite 116 may be any of a wide variety of data, including, but not limited to, digital image data, including video data, audio data, and data provided by sensors, radars, telescopes, and radio receivers. In at least some cases, the data is encoded prior to transmission via the uplink and downlink beams and decoded after reception. The resulting data received may be used for a variety of purposes, including presenting the data to a user, storing the data for subsequent use, and / or supplying the data to one or more applications, such as applications that perform statistical inference on the data for a variety of purposes, including object recognition, image classification, spectral sensing, speech transcription, and / or event prediction or detection.

[0040] Figure 1 1 shows a user equipment 110 (also referred to as UE, user device, user terminal, terminal device, etc.) illustrating the type of device to which resources on the air interface are allocated or assigned. User equipment 110 generally refers to a portable computing device, which includes wireless mobile communication devices that operate with or without a subscriber identity module (SIM), including but not limited to the following types of devices: mobile stations (mobile phones), smart phones, personal digital assistants (PDAs), mobile phones, devices using wireless modems (alarm or measurement devices, etc.), laptops and / or touch screen computers, tablets, game consoles, notebook computers, and multimedia devices. User equipment 110 may also be a device with the ability to operate in an Internet of Things (IoT) network, in which an object has the ability to transmit data on a network without the need for human-to-human or human-to-computer interaction. User equipment 110 may also be referred to as a subscriber unit, a mobile station, a remote terminal, an access terminal, a user terminal, or a user equipment (UE), to name a few. User equipment 110 may be connected via radio resource control. The user equipment may be in a radio resource control inactive mode or a radio resource control idle mode.

[0041] Figure 1 The network nodes 112 and 115 may include, for example, a base station, such as a remote radio head (RRH), a transmission reception point (TRP), an access point, a NodeB (e.g., a gNB), or other transmission sources. The network nodes 112 and 115 may be configured to communicate with the user equipment 110 via a network.

[0042] Source satellite 114 and target satellite 116 may be configured to relay signals from, for example, network node 112 or 115 to user equipment 110. Source satellite 114 and target satellite 116 may have a transparent structure in which signals are relayed from network nodes 112, 115, and / or different network nodes to user equipment 110, or they may have a regenerative structure in which, for example, network node 112 is onboard source satellite 114 and network node 115 is onboard target satellite 116.

[0043] Figure 2 An example apparatus 200 is depicted, which may be configured for use as a user equipment 110 or centralized and distributed network nodes 112-118. Figure 2 As shown in , the device includes a processing circuit system 220, a memory 240 and a communication interface 260, is associated with it, or communicates with it. The processing circuit system 220 can communicate with the memory device 240 via a bus to transfer information between components of the device. The memory device can be non-transient and can include, for example, one or more volatile and / or non-volatile memories. In other words, for example, the memory device can be an electronic storage device (e.g., a computer-readable storage medium) that includes a gate configured to store data (e.g., bits) that can be retrieved by a machine (e.g., a computing device such as a processing circuit system). The memory device can be configured to store information, data, content, applications, instructions, etc., so that the device can perform various functions according to the example embodiments of the present disclosure. For example, the memory device can be configured to buffer input data for processing by the processing circuit system. Additionally or alternatively, the memory device can be configured to store instructions executed by the processing circuit system.

[0044] In some embodiments, the device 200 may be embodied in various computing devices as described above. However, in some embodiments, the device may be embodied as a chip or a chipset. In other words, the device may include one or more physical packages (e.g., chips), including materials, components, and / or wires on a structural assembly (e.g., a substrate). The structural assembly may provide physical strength, dimensional conservation, and / or limitations on electrical interactions for the component circuitry included thereon. Therefore, in some cases, the device may be configured to implement an embodiment on a single chip or as a single "system on a chip". Therefore, in some cases, a chip or chipset may constitute a component for performing one or more operations to provide the functionality described herein.

[0045] The processing circuit system 220 (also referred to as a processor) can be embodied in a variety of different ways. For example, the processing circuit system can be embodied as one or more of various hardware processing components, such as a coprocessor, a microprocessor, a controller, a digital signal processor (DSP), a processing element with or without a DSP, or various other circuit systems including integrated circuits, such as ASICs (application-specific integrated circuits), FPGAs (field programmable gate arrays), microcontroller units (MCUs), hardware accelerators, special-purpose computer chips, etc. Therefore, in some embodiments, the processing circuit system may include one or more processing cores configured to execute independently. The multi-core processing circuit system can enable multi-processing within a single physical package. Additionally or alternatively, the processing circuit system may include one or more processors configured in series via a bus to enable independent execution, pipelining, and / or multi-threading of instructions.

[0046] In an example embodiment, the processing circuit system 220 may be configured to execute instructions stored in the memory device 240 or instructions that the processing circuit system is otherwise accessible to. Alternatively or additionally, the processing circuit system may be configured to perform hard-coded functions. Therefore, whether configured by hardware or software methods, or by a combination thereof, the processing circuit system may represent an entity (e.g., physically embodied in a circuit system) that is capable of performing operations according to an embodiment of the present disclosure when configured accordingly. Therefore, for example, when the processing circuit system is embodied as an ASIC, FPGA, etc., the processing circuit system may be specially configured hardware for performing the operations described herein. Alternatively, as another example, when the processing circuit system is embodied as an executor of instructions, the instructions may specifically configure the processor to perform the algorithms and / or operations described herein when the instructions are executed. However, in some cases, the processing circuit system may be a processor of a specific device (e.g., an image or video processing system) that is configured to further configure the processing circuit system to adopt an embodiment by executing instructions for the algorithms and / or operations described herein. The processing circuitry may include, among other things, a clock, an arithmetic logic unit (ALU), and logic gates configured to support operation of the processing circuitry.

[0047] The communication interface 260 can be any component, such as a device or circuit system embodied in hardware or a combination of hardware and software, which is configured to receive and / or send data, including media content in the form of video or image files, one or more audio tracks, etc. In this regard, for example, the communication interface may include an antenna (or multiple antennas) and supporting hardware and / or software for enabling communication with a wireless communication network. Additionally or alternatively, the communication interface may include a circuit system for interacting with (multiple) antennas to enable signal transmission via (multiple) antennas or processing reception of signals received via (multiple) antennas. In some environments, the communication interface may alternatively or additionally support wired communications. Therefore, for example, the communication interface may include a communication modem and / or other hardware / software to support communication via cable, digital subscriber line (DSL), universal serial bus (USB), or other mechanisms.

[0048] Now go to Figure 3 , an example illustration of a non-terrestrial network 300 is provided according to the previous embodiment. A data network 350 is connected to a gateway 340. The gateway 340 sends a signal to a satellite 330 (or an unmanned aerial system 330) via a feeder link. The signal is relayed via a service link to cover a beam footprint 320. Multiple beam footprints constitute the field of view of a satellite 330. A user device 310 may be mobile or stationary on the earth and may leave the field of view of a satellite 330 and enter the field of view of a different satellite. In the field of view of a satellite 330, transmissions from a user device 310 may also be relayed to the gateway 340 and the data network 350 via the satellite 330.

[0049] Now go to Figure 4A , according to the previous embodiment, an example of satellite handover is shown, in which the primary cell identifier does not change in a transparent earth-fixed cell deployment. In this case, the user equipment 110 is served by the satellite 440. The satellite 440 and the satellite 430 are each configured to relay a signal from the network node 112 sent via the gateway 420. As the satellite 440 moves away from the user equipment 110 and the satellite 430 approaches, the network node 112 indicates that a satellite handover may occur and how to perform resynchronization with the new cell. After the satellite 430 takes over the area serving the user equipment 110, the user equipment 110 performs downlink and uplink synchronization operations to reconnect.

[0050] Since the user equipment 110 does not change the serving network node 112, it maintains the same cell configuration. Satellites 430 and 440 are configured with the same physical cell identifier, the same user equipment context, and the same protocol stack (including synchronization signal block generation, encoding and decoding, modulation and demodulation, control resource set configuration, and switch routing). However, from the reference point of the user equipment 410, the satellites 430 and 440 introduce different frequencies (i.e., Doppler) and timing drifts (the propagation paths toward the satellites 430 and 440 are different).

[0051] In some cases, user equipment 110 performs a hard satellite handover that takes into account the absence of overlap between non-terrestrial network cells radiated by satellites 430 and 440. In this case, user equipment 110 should take into account a certain interruption time to pre-compensate the frequency and timing of the new cell. In other cases, user equipment 110 performs a soft satellite handover that takes into account cell overlap. In this scenario, it is assumed that satellites 430 and 440 are transmitting synchronization signal blocks at the same time (possibly with the same physical cell identifier, but with different time and frequency offsets to allow the user equipment to switch satellites).

[0052] Now go to Figure 4B , an example is shown in which a satellite 430 is connected to another network node 115 different from the network node 112 connected to a satellite 440. In the example shown, the satellite has a regenerative architecture in which network nodes 115 and 112 are located on satellites 430 and 440, respectively. However, a transparent architecture is also possible in which network nodes 115 and 112 send signals to satellites 430 and 440, respectively, through a gateway 420.

[0053] Now go to Figure 5 According to the previous embodiment, a system information block 500 containing satellite assistance information for non-terrestrial network access is provided. The system information block 500 is a SIB19 information element.

[0054] The system information block 500 includes a reference field 510 distanceThresh. The reference field 510 describes the distance from the serving cell reference position and is used for location-based measurement initiation for both radio resource control idle mode and radio resource control active mode. Each step represents 50 meters.

[0055] The system information block 500 includes a reference field 520 ntn-Config. The reference field 520 provides parameters required by the user equipment to access the new radio via non-terrestrial network access, such as ephemeris data, common timing advance parameters, k_offset, and valid duration for uplink synchronization information and epochs.

[0056] System information block 500 includes reference fields 530a ntn-NeighCellConfigList and 530b ntn-NeighCellConfigListExt. Reference fields 530a and 530b provide a list of non-terrestrial network neighboring cells, including their non-terrestrial network configurations, carrier frequencies, and physical cell identifiers. If the entry in reference field 530b does not have a non-terrestrial network configuration, the non-terrestrial network configuration provided in the entry at the same position in reference field 530a applies. The non-terrestrial configuration of the first entry of reference field 530a is provided by the network. If any other entry in reference field 530a does not have a non-terrestrial configuration, the non-terrestrial configuration provided in the previous entry of reference field 530a applies.

[0057] The system information block 500 includes a reference field 540 referenceLocation. The reference field 540 describes a reference location of a serving cell provided via a non-terrestrial network quasi-geo-fixed system and is used for location-based measurement initiation in a radio resource control idle mode and a radio resource control inactive mode.

[0058] The system information block 500 includes a reference field 550t-Service. The reference field 550 indicates time information when a cell provided via a non-terrestrial network quasi-geo-fixed system stops providing services to the area currently covered by it. This field indicates the time after 00:00:00 on January 1, 1900 in the Gregorian calendar (midnight between Sunday, December 31, 1899 and Monday, January 1, 1900), in units of multiples of 10 ms. The exact stop time is between the time indicated by the value of this field minus 1 and the time indicated by the value of this field.

[0059] Now go to Fig. 6A , illustrates a medium access control element 600 for random access channel retry according to the previous embodiment. If the random access channel access fails, for example, due to another user equipment accessing the same random access channel resource, the user equipment receives a re-authorization request from the network, but the random access preamble identifier may not be applicable to it. There is likely to be a backoff indicator value sent together with the re-authorization request to control the physical random access channel retransmission timing.

[0060] The backoff indicator 610 is used to indicate when the user equipment performs a random access channel retry. The backoff indicator 610 shown is for long term evolution, but the same principles apply to new radio. The backoff indicator 610 is a subheader that carries the time delay between the physical random access channel and the next physical random access channel. The backoff indicator 610 is illustrated as consisting of 4 bits, which means that it can carry a value of 0 to 15. Each value is mapped to Figure 6BThe specific time shown in .

[0061] Now go to Figure 6B , illustrates a table showing the correlation between the backoff indicator field value 620 and the backoff parameter value 630. For example, if the backoff indicator field value 620 is 10, the backoff parameter value 630 is 320ms. This means that the user equipment can send the physical random access channel at any time between 0 and 320ms.

[0062] Now go to Figure 7 , according to an exemplary embodiment of the present disclosure, a diagram 700 of a user equipment accessing a target satellite at a specific access time is provided;

[0063] In one or more embodiments, the user device 110 is connected to the source satellite 114. However, in some examples, the source satellite 114 may be moving away from the user device 110. In other examples, the user device 110 may be moving away from the source satellite 114. In these examples, the user device needs to switch from the source satellite 114 to the target satellite 116. In some examples, the user device 110 may need to perform a random access channel access of the target satellite 116. In some examples, the target satellite 116 may be connected to a common network node with the source satellite 114, while in other examples, the target satellite 116 may be connected to a different network node than the source satellite 114 (e.g., with a transparent or regenerative architecture). For example, the user device 110 may not be able to perform a random access channel-free access. In other examples, the user device 110 may be able to perform a random access channel-free access, but chooses to perform a random access channel-based access. For example, the user equipment 110 may choose to perform random access channel-based access after experiencing a failure to access without a random access channel (e.g., because the user equipment did not receive a configured grant, the target cell was unavailable at the first configured grant opportunity, network resource allocation was poor, radio link conditions were poor, reference signal received power dropped below a threshold, etc.). In some examples, the network node connected to the source satellite 114 may know the proportion of user equipment devices that perform random access channel-based access, while in other examples, the network node does not know this. In some examples, the network node roughly knows the percentage of user equipment devices that have no random access channel capability.

[0064] In one or more embodiments, the source satellite 114 sends a system information block (i.e., system information block 19) to the user equipment 110 that includes target satellite switching related parameters. In some examples, the system information block includes an indicator of the random access channel opportunity window 720. For example, the system information block may indicate a maximum access delay time that describes the maximum time that the user equipment 110 must access the target satellite 116 after the satellite switching time. Alternatively, the system information block may indicate the maximum time that the user equipment 110 can access the target satellite 116 before the satellite switching time. In some examples, the system information block indicates the number of random access channel opportunities instead of the time window. In some examples, at least one opportunity is associated with a user equipment identifier assigned to the user equipment 110.

[0065] In some examples, the satellite switching time is a service stop time 710 associated with the source satellite 114. For example, at the service stop time 710, the user device 110 is no longer in the coverage area of ​​the source satellite 114. In other examples, the satellite switching time is a service start time associated with the target satellite 116. For example, at the service start time, the user device 110 enters the coverage area of ​​the target satellite 116.

[0066] In some examples, the system information block also indicates a minimum access time after the satellite switching time. For example, the system information block may indicate an additional delay to be added to avoid access immediately after the satellite switching time.

[0067] In some examples, the random access channel opportunity window 720 is allocated to a user equipment device group. For example, a higher priority user equipment group can obtain a shorter or earlier random access channel opportunity window 720 than a lower priority user equipment group. For example, a higher priority user equipment group can obtain a lower maximum access delay time than a lower priority user equipment group. In another example, different minimum access times can be assigned to different user equipment groups. In another example, different random access channel opportunities within the random access channel opportunity window 720 can be associated with different user equipment identifiers (i.e., different values ​​of the last (multiple) digits of the calling radio network temporary identifier are mapped to different random access channel opportunities).

[0068] In one or more embodiments, the user equipment 110 reads a system information block. For example, the user equipment 110 may read a maximum access delay time from the system information block. In another example, the user equipment 110 may read a minimum access time from the system information block. In some examples, the user equipment 110 may read a maximum access delay time and / or a minimum access time assigned to the user equipment 110 or a user equipment device group including the user equipment 110.

[0069] In one or more embodiments, the user equipment 110 determines an access time, which is a uniformly distributed random time (i.e., UE_access_time) within the random access channel opportunity window 720 (e.g., between the minimum access time and the maximum access delay time). In some examples, the user equipment accesses the target satellite 116 at this time. In some examples, by uniformly distributing the random access channel access time, the random access channel resources are distributed over time. For example, this can avoid a random access channel storm from too many user equipment devices performing random access channel-based access at one time. In some examples, the user equipment 110 determines the access time using a determination method preconfigured by the user equipment 110, rather than a uniformly distributed random time. In some examples, the user equipment 110 determines the access time using a determination method provided by the network node through the target satellite 114, rather than using a uniformly distributed random time. In some examples, the access time within the random access channel opportunity window (e.g., before or after the satellite switching time).

[0070] Now go to Fig. 8A , which is a flow chart 800a of system information block based random access with hard satellite handover according to an example embodiment of the present disclosure. In one or more embodiments, flow chart 800a illustrates that a group of user equipment devices 110a-c performs a hard satellite handover between a source satellite and a target satellite. In this example embodiment, the source satellite and the target satellite have a transparent structure and are connected to a common network node 112. However, in other examples, the source satellite and the target satellite may be connected to separate network nodes (e.g., network nodes 112 and 115) via a transparent structure or a regenerative structure (i.e., the network node is on the satellite).

[0071] In one or more embodiments, at operation 805, the network node sends a system information block 805a to the user equipment device 110a-c via the source satellite. In some examples, the system information block 805a indicates a random access channel opportunity window 855. In some examples, the random access channel opportunity window 855 is indicated by identifying a service stop time 810 associated with the source satellite and a maximum delay time 850, in which the user equipment device 110a-c can perform a satellite handover after the service stop time 810. In other examples, the random access channel opportunity window 855 may start at a service start time associated with the target satellite. In other examples, the system information block may identify a gap time (i.e., a minimum delay time) after the service stop time 810 or a service start time before the random access channel opportunity window 855 starts. In some examples, the requirement for the maximum interruption delay is modified to include the random access channel opportunity window 855.

[0072] In this example, user equipment devices 110a and 110c determine to perform random access channel-based access. In this example, user equipment device 110b determines to initially perform access without random access channel. In one or more embodiments, user equipment devices 110a and 110c determine uniform random access times 815 and 825 within random access channel opportunity window 855, respectively. In one or more embodiments, this saves random access channel resources by allowing user equipment devices 110a and 110c to perform random access channel-based access at different times. In other examples, access times 815 and 825 can be determined using a determination method preconfigured by user equipment 110 or provided by network node 112.

[0073] In one or more embodiments, at operation 820, the user equipment 110a performs random access-based access to the network node 112 via the target satellite. For example, the user equipment 110a transmits a random access preamble 820a to the access network node 112 via the target satellite at access time 815.

[0074] In one or more embodiments, at operation 830, the user equipment 110c performs random access-based access to the network node 112 via the target satellite. For example, the user equipment 110c transmits a random access preamble 840a to the access network node 112 via the target satellite at access time 825.

[0075] In one or more embodiments, at operation 835, the user equipment 110b is unsuccessful in the random access channel access attempt. For example, the user equipment 110b may experience a random access channel access failure due to the user equipment 110b not receiving a configured grant, the target cell being unavailable at the first configured grant opportunity, poor network resource allocation, poor radio link conditions, reference signal received power falling below a threshold, etc. In one or more embodiments, the user equipment 110b then determines that the random access channel opportunity window 855 is still in progress. In response, the user equipment 110b then determines a uniformly distributed random time 840 between the time when the random access channel access failure 835 is detected and the end of the random access channel opportunity 855. In other embodiments, the time 840 can be determined using a determination method preconfigured by the user equipment 110 or provided by the network node 112. In an alternative example, the random access channel opportunity window 855 can be delayed until the time when the random access channel access failure 835 is detected.

[0076] In one or more embodiments, at operation 845, the user equipment 110b performs random access-based access to the network node 112 via the target satellite. For example, the user equipment 110b transmits a random access preamble 845a to the access network node 112 via the target satellite at access time 840.

[0077] Now go to Figure 8B , which is a flow chart 800b of system information block based random access with soft satellite handover according to an example embodiment of the present disclosure. In one or more embodiments, flow chart 800b illustrates a group of user equipment devices 110a-c performing a soft satellite handover between a source satellite and a target satellite. In this example embodiment, the source satellite and the target satellite have a transparent structure and are connected to a common network node 112. However, in other examples, the source satellite and the target satellite may be connected to separate network nodes (e.g., network nodes 112 and 115) via a transparent structure or a regenerative structure (i.e., the network node is on the satellite).

[0078] In one or more embodiments, at operation 805, the network node sends a system information block 805a to the user equipment device 110a-c via the source satellite. In some examples, the system information block 805a indicates a random access channel opportunity window 855. In some examples, the random access channel opportunity window 855 is indicated by identifying a service start time 860 associated with the target satellite and a maximum delay time 850 during which the user equipment device 110a-c may perform a satellite handover after the service start time 850. In this example, the random access channel opportunity window 855 begins after a gap time 865 after the service start time 860. In some examples, the random access channel opportunity window 855 may be comprised of a service outage time 810 associated with the source satellite, a maximum time 870 that the user equipment device 110a-c may perform a satellite handover before the service outage time 810, and a maximum delay time 875 that the user equipment device 110a-c may perform a satellite handover after the service end time 810 if the user equipment 110a-c does not perform a satellite handover before the service outage time 810. In some examples, the maximum delay time 875 extends beyond another reference time point. In some examples, the requirement for the maximum outage delay is modified to include the random access channel opportunity window 855.

[0079] In this example, user equipment devices 110a and 110c determine to perform random access channel-based access. In this example, user equipment device 110b determines to initially perform access without random access channel. In one or more embodiments, user equipment devices 110a and 110c determine uniform random access times 815 and 825 within random access channel opportunity window 855, respectively. In one or more embodiments, this saves random access channel resources by allowing user equipment devices 110a and 110c to perform random access channel-based access at different times. In other examples, access times 815 and 825 can be determined using a determination method preconfigured by user equipment 110 or provided by network node 112.

[0080] In one or more embodiments, at operation 820, the user equipment 110a performs random access-based access to the network node 112 via the target satellite. For example, the user equipment 110a transmits a random access preamble 820a to the access network node 112 via the target satellite at access time 815.

[0081] In one or more embodiments, at operation 830, the user equipment 110c performs random access-based access to the network node 112 via the target satellite. For example, the user equipment 110c transmits a random access preamble 840a to the access network node 112 via the target satellite at access time 825.

[0082] In one or more embodiments, at operation 835, the user equipment 110b is unsuccessful in the random access channel access attempt. For example, the user equipment 110b may experience a random access channel access failure due to the user equipment 110b not receiving a configured grant, the target cell being unavailable at the first configured grant opportunity, poor network resource allocation, poor radio link conditions, reference signal received power falling below a threshold, etc. In one or more embodiments, the user equipment 110b then determines that the random access channel opportunity window 855 is still in progress. In response, the user equipment 110b then determines a uniformly distributed random time 840 between the time when the random access channel access failure 835 is detected and the end of the random access channel opportunity 855. In other embodiments, the time 840 can be determined using a determination method preconfigured by the user equipment 110 or provided by the network node 112. In an alternative example, the random access channel opportunity window 855 can be delayed until the time when the random access channel access failure 835 is detected.

[0083] In one or more embodiments, at operation 845, the user equipment 110b performs random access-based access to the network node 112 via the target satellite. For example, the user equipment 110b transmits a random access preamble 845a to the access network node 112 via the target satellite at access time 840.

[0084] Now go to Fig. 9 According to an exemplary embodiment of the present disclosure, a system information block 900 indicating a random access channel opportunity window is provided. In one or more embodiments, a reference field 910 indicates the random access channel opportunity window. For example, the reference field 910 may indicate the random access channel opportunity window by indicating a maximum delay time after a satellite switching time during which a user equipment may perform access based on a random access channel.

[0085] Now go to Fig.10 , illustrates an example flow diagram of a process 1000 performed by an apparatus embodied by, associated with, or otherwise in communication with a user equipment (110) to transmit a random access channel preamble at an access time.

[0086] like Fig.10As shown in block 1010 of , an apparatus embodied by a user equipment (110) includes means, such as processing circuitry (220), a communication interface (260), etc., for receiving (805) a system information block (805a) from a first network node (112) via a source satellite, wherein the system information block (805a) indicates a random access channel opportunity window (855) within which the user equipment (110a / 110b / 110c) should access the first network node (112) or the second network node. In one or more embodiments, the random access channel opportunity window (855) includes a maximum delay time (850) during which the user equipment (110a / 110b / 110c) accesses the first network node (112) or the second network node after a satellite switching time (810 / 860), the satellite switching time (810 / 860) being one of a service stop time (810) associated with the source satellite or a service start time (860) associated with the target satellite. In one or more embodiments, the random access channel opportunity window (855) begins at a minimum delay time (865) after the satellite switching time (810 / 860). In one or more embodiments, the random access channel opportunity window (855) includes a maximum time (870) that the user equipment (110a / 110b / 110c) can access the first network node (112) or the second network node before the service stop time (810) associated with the source satellite. In one or more embodiments, the random access channel opportunity window (855) ends at a maximum delay time (850 / 875) after the service stop time (810) or the service start time (860) associated with the target satellite. In one or more embodiments, the random access channel opportunity window (855) is allocated to a specific user equipment device group including the user equipment (110a / 110b / 110c). In one or more embodiments, the random access channel opportunity window (855) includes a plurality of random access channel opportunities for performing random access channel based access. In one or more embodiments, at least one random access channel opportunity of the plurality of random access channel opportunities is associated with a user equipment identifier assigned to the user equipment (110a / 110b / 110c).

[0087] like Fig.10As shown in block 1020 of , an apparatus embodied by a user equipment (110) includes components, such as a processing circuit system (220), a communication interface (260), etc., for determining an access time (815 / 825 / 840) within a random access channel opportunity window (855) based on a system information block (805a). In one or more embodiments, the access time (815 / 825 / 840) is a uniformly distributed random time within the random access channel opportunity window (855). In one or more embodiments, the access time (815 / 825 / 840) is determined by a determination method preconfigured by the user equipment (110a / 110b / 110c). In one or more embodiments, the random access channel opportunity window (855) is delayed (835) based on a time when there is no random access channel access failure.

[0088] like Fig.10 As shown in block 1030 of , an apparatus embodied by a user equipment (110) includes means, such as processing circuitry (220), a communication interface (260), etc., for sending (820 / 830 / 845) a random access channel preamble (820a / 830a / 845a) to a first network node (112) or a second network node via a target satellite at an access time (815 / 825 / 840). In one or more embodiments, the user equipment (110b) determines the access time (840) and sends (820 / 830 / 845) the random access channel preamble (820a / 830a / 845a) in response to a no random access channel access failure (835).

[0089] Now go to Fig.11 , illustrates an example flow chart of a process 1100 performed by an apparatus embodied by, associated with, or otherwise in communication with (hereinafter generally referred to as embodied by) a network node (112) to receive a random access channel preamble at an access time.

[0090] like Fig.11As shown in block 1110 of , an apparatus embodied by a network node (112) includes means, such as processing circuitry (220), a communication interface (260), etc., for sending (805) a system information block (805a) to a user equipment (110a / 110b / 110c) via a source satellite, wherein the system information block (805a) indicates a random access channel opportunity window (855) in which the user equipment (110a / 110b / 110c) should access a first network node (112) or another network node via a target satellite (116). In one or more embodiments, the random access channel opportunity window (855) includes a maximum delay time (850) during which the user equipment (110a / 110b / 110c) accesses the network node (112) or the second network node after a satellite switching time (810 / 860), the satellite switching time (810 / 860) being one of a service stop time (810) associated with a source satellite or a service start time (860) associated with a target satellite (112). In one or more embodiments, the random access channel opportunity window (855) starts at a minimum delay time (865) after the satellite switching time (810 / 860). In one or more embodiments, the random access channel opportunity window (855) includes a maximum time (870) that the user equipment (110a / 110b / 110c) can access the network node (112) or another network node before the service stop time (810) associated with the source satellite. In one or more embodiments, the random access channel opportunity window (855) ends at a maximum delay time (850 / 875) after a service stop time (810) or a service start time (860) associated with a target satellite. In one or more embodiments, the random access channel opportunity window (855) is allocated to a specific user equipment device group including the user equipment (110a / 110b / 110c). In one or more embodiments, the random access channel opportunity window (855) includes a plurality of random access channel opportunities for performing random access channel-based access. In one or more embodiments, at least one random access channel opportunity of the plurality of random access channel opportunities is associated with a user equipment identifier allocated to the user equipment (110a / 110b / 110c).

[0091] like Fig.11As shown in block 1120 of , the apparatus embodied by the network node (112) includes means, such as processing circuitry (220), communication interface (260), etc., for receiving (820 / 830 / 845) a random access channel preamble (820a / 830a / 845a) from a user equipment (110a / 110b / 110c) via a target satellite at an access time (815 / 825 / 840) within a random access channel opportunity window (855). In one or more embodiments, the access time (815 / 825 / 840) is a uniformly distributed random time within the random access channel opportunity window (855). In one or more embodiments, the access time (815 / 825 / 840) is determined by a determination method preconfigured by the user equipment (110a / 110b / 110c). In one or more embodiments, the network node (112) is further caused to: determine a method for determining a user equipment (110) to determine an access time (815 / 825 / 840), wherein the determined time is indicated by a system information block (805a). In one or more embodiments, the user equipment (110b) determines the access time (840) and sends (820 / 830 / 845) a random access channel preamble (820a / 830a / 845a) in response to no random access channel access failure (835). In one or more embodiments, the random access channel opportunity window (855) is delayed based on the time when there is no random access channel access failure (835).

[0092] Figure 10-11A flowchart describing a method according to an example embodiment of the present disclosure is illustrated. It should be understood that each block of the flowchart and the combination of blocks in the flowchart can be implemented in various ways, such as hardware, firmware, processor, circuit system, and / or other communication devices associated with the execution of software including one or more computer program instructions. For example, one or more of the above processes can be implemented by computer program instructions. In this regard, the computer program instructions embodying the above processes can be stored by the memory device 240 of the device using the embodiment and executed by the processor 220. As will be understood, any such computer program instructions can be loaded into a computer or other programmable device (e.g., hardware) to produce a machine so that the resulting computer or other programmable device implements the functions specified in the flowchart blocks. These computer program instructions can also be stored in a computer-readable memory, which can instruct a computer or other programmable device to operate in a specific manner so that the instructions stored in the computer-readable memory produce an article, and the execution of the article implements the functions specified in the flowchart blocks. Computer program instructions may also be loaded into a computer or other programmable device to cause a series of operations to be performed on the computer or other available device to produce a computer-implemented process, so that the instructions executed on the computer or other programmable device provide operations for implementing the functions specified in the flowchart block.

[0093] Therefore, the block of flow chart supports the combination of the components for performing the specified functions and the combination of the operations for performing the specified functions. It will also be understood that the combination of one or more blocks of the flow chart and the blocks in the flow chart can be implemented by a computer system based on special-purpose hardware that performs the specified functions, or a combination of special-purpose hardware and computer instructions.

[0094] In one or more embodiments, a user equipment (110a / 110b / 110c) is provided, the user equipment comprising at least one processor and at least one memory storing instructions, the instructions, when executed by the processor, causing the user equipment (110a / 110b / 110c) to: receive (805) a system information block (805a) from a first network node (112) via a source satellite, wherein the system information block (805a) indicates a random access channel opportunity window (855), in which the user equipment (110a / 110b / 110c) should access the first network node (112) or a second network node. The user equipment (110a / 110b / 110c) is also caused to: determine an access time (815 / 825 / 840) within the random access channel opportunity window (855) based on the system information block (805a). The user equipment (110a / 110b / 110c) is also caused to send (820 / 830 / 845) a random access channel preamble (820a / 830a / 845a) to the first network node (112) or the second network node via the target satellite at the access time (815 / 825 / 840).

[0095] In one or more embodiments, the random access channel opportunity window (855) includes a maximum delay time (850) during which the user equipment (110a / 110b / 110c) accesses the first network node (112) or the second network node after a satellite switching time (810 / 860), the satellite switching time (810 / 860) being one of a service stop time (810) associated with a source satellite or a service start time (860) associated with a target satellite.

[0096] In one or more embodiments, the random access channel opportunity window (855) begins at a minimum delay time (865) after the satellite switch time (810 / 860).

[0097] In one or more embodiments, the random access channel opportunity window (855) includes a maximum time (870) that a user device (110a / 110b / 110c) can access the first network node (112) or the second network node before a service outage time (810) associated with the source satellite.

[0098] In one or more embodiments, the random access channel opportunity window (855) ends a maximum delay time (850 / 875) after the service stop time (810) or the service start time (860) associated with the target satellite.

[0099] In one or more embodiments, the random access channel opportunity window (855) is allocated to a specific group of user equipment devices including the user equipment (110a / 110b / 110c).

[0100] In one or more embodiments, the access times (815 / 825 / 840) are uniformly distributed random times within the random access channel opportunity window (855).

[0101] In one or more embodiments, the access time (815 / 825 / 840) is determined by a determination method preconfigured by the user equipment (110a / 110b / 110c).

[0102] In one or more embodiments, the user equipment (110b) determines an access time (840) and sends (820 / 830 / 845) a random access channel preamble (820a / 830a / 845a) in response to no random access channel access failure (835).

[0103] In one or more embodiments, the random access channel opportunity window (855) is delayed based on a time when there are no random access channel access failures (835).

[0104] In one or more embodiments, the random access channel opportunity window (855) includes a plurality of random access channel opportunities for performing random access channel based access.

[0105] In one or more embodiments, at least one random access channel opportunity of the plurality of random access channel opportunities is associated with a user equipment identifier assigned to the user equipment (110a / 110b / 110c).

[0106] In one or more embodiments, a network node (112) is provided, the network node comprising at least one processor and at least one memory storing instructions, the instructions, when executed by the processor, causing the network node (112) to: send (805) a system information block (805a) to a user equipment (110a / 110b / 110c) via a source satellite, wherein the system information block (805a) indicates a random access channel opportunity window (855) in which the user equipment (110a / 110b / 110c) should access the network node (112) or another network node via a target satellite (116). Additionally or alternatively, the network node (112) may be caused to: receive (820 / 830 / 845) a random access channel preamble (820a / 830a / 845a) from the user equipment (110a / 110b / 110c) via the target satellite at an access time (815 / 825 / 840) within the random access channel opportunity window (855).

[0107] In one or more embodiments, the random access channel opportunity window (855) includes a maximum delay time (850) during which the user equipment (110a / 110b / 110c) accesses the network node (112) or the second network node after a satellite switching time (810 / 860), the satellite switching time (810 / 860) being one of a service stop time (810) associated with a source satellite or a service start time (860) associated with a target satellite (112).

[0108] In one or more embodiments, the random access channel opportunity window (855) begins at a minimum delay time (865) after the satellite switch time (810 / 860).

[0109] In one or more embodiments, the random access channel opportunity window (855) includes a maximum time (870) that a user device (110a / 110b / 110c) can access the network node (112) or another network node before a service outage time (810) associated with a source satellite.

[0110] In one or more embodiments, the random access channel opportunity window (855) ends a maximum delay time (850 / 875) after the service stop time (810) or the service start time (860) associated with the target satellite.

[0111] In one or more embodiments, the random access channel opportunity window (855) is allocated to a specific group of user equipment devices including the user equipment (110a / 110b / 110c).

[0112] In one or more embodiments, the access times (815 / 825 / 840) are uniformly distributed random times within the random access channel opportunity window (855).

[0113] In one or more embodiments, the network node (112) is further caused to: determine a determination method used by the user equipment (110) to determine an access time (815 / 825 / 840), wherein the determined time is indicated by a system information block (805a).

[0114] In one or more embodiments, the user equipment (110b) determines an access time (840) and sends (820 / 830 / 845) a random access channel preamble (820a / 830a / 845a) in response to no random access channel access failure (835).

[0115] In one or more embodiments, the random access channel opportunity window (855) is delayed based on a time when there are no random access channel access failures (835).

[0116] In one or more embodiments, the random access channel opportunity window (855) includes a plurality of random access channel opportunities for performing random access channel based access.

[0117] In one or more embodiments, at least one random access channel opportunity of the plurality of random access channel opportunities is associated with a user equipment identifier assigned to the user equipment (110a / 110b / 110c).

[0118] In one or more embodiments, a computer-implemented method performed by a user equipment (110a / 110b / 110c) is provided, the method comprising: receiving (805) a system information block (805a) from a first network node (112) via a source satellite, wherein the system information block (805a) indicates a random access channel opportunity window (855) during which the user equipment (110a / 110b / 110c) should access the first network node (112) or a second network node. The method further comprises: determining an access time (815 / 825 / 840) within the random access channel opportunity window (855) based on the system information block (805a). The method further comprises: sending (820 / 830 / 845) a random access channel preamble (820a / 830a / 845a) to the first network node (112) or the second network node via a target satellite at the access time (815 / 825 / 840).

[0119] In one or more embodiments, the random access channel opportunity window (855) includes a maximum delay time (850) during which the user equipment (110a / 110b / 110c) accesses the first network node (112) or the second network node after a satellite switching time (810 / 860), the satellite switching time (810 / 860) being one of a service stop time (810) associated with a source satellite or a service start time (860) associated with a target satellite.

[0120] In one or more embodiments, the random access channel opportunity window (855) begins at a minimum delay time (865) after the satellite switch time (810 / 860).

[0121] In one or more embodiments, the random access channel opportunity window (855) includes a maximum time (870) that a user device (110a / 110b / 110c) can access the first network node (112) or the second network node before a service outage time (810) associated with the source satellite.

[0122] In one or more embodiments, the random access channel opportunity window (855) ends a maximum delay time (850 / 875) after the service stop time (810) or the service start time (860) associated with the target satellite.

[0123] In one or more embodiments, the random access channel opportunity window (855) is allocated to a specific group of user equipment devices including the user equipment (110a / 110b / 110c).

[0124] In one or more embodiments, the access times (815 / 825 / 840) are uniformly distributed random times within the random access channel opportunity window (855).

[0125] In one or more embodiments, the access time (815 / 825 / 840) is determined by a determination method preconfigured by the user equipment (110a / 110b / 110c).

[0126] In one or more embodiments, the user equipment (110b) determines an access time (840) and sends (820 / 830 / 845) a random access channel preamble (820a / 830a / 845a) in response to no random access channel access failure (835).

[0127] In one or more embodiments, the random access channel opportunity window (855) is delayed based on a time when there are no random access channel access failures (835).

[0128] In one or more embodiments, the random access channel opportunity window (855) includes a plurality of random access channel opportunities for performing random access channel based access.

[0129] In one or more embodiments, at least one random access channel opportunity of the plurality of random access channel opportunities is associated with a user equipment identifier assigned to the user equipment (110a / 110b / 110c).

[0130] In one or more embodiments, a computer-implemented method performed by a network node (112) is provided, the method comprising: sending (805) a system information block (805a) to a user equipment (110a / 110b / 110c) via a source satellite, wherein the system information block (805a) indicates a random access channel opportunity window (855) during which the user equipment (110a / 110b / 110c) should access the network node (112) or another network node via a target satellite. Additionally or alternatively, the method comprises: receiving (820 / 830 / 845) a random access channel preamble (820a / 830a / 845a) from the user equipment (110a / 110b / 110c) via the target satellite at an access time (815 / 825 / 840) within the random access channel opportunity window (855).

[0131] In one or more embodiments, the random access channel opportunity window (855) includes a maximum delay time (850) during which the user equipment (110a / 110b / 110c) accesses the network node (112) or the second network node after a satellite switching time (810 / 860), the satellite switching time (810 / 860) being one of a service stop time (810) associated with a source satellite or a service start time (860) associated with a target satellite (112).

[0132] In one or more embodiments, the random access channel opportunity window (855) begins at a minimum delay time (865) after the satellite switch time (810 / 860).

[0133] In one or more embodiments, the random access channel opportunity window (855) includes a maximum time (870) that a user device (110a / 110b / 110c) can access the network node (112) or another network node before a service outage time (810) associated with a source satellite.

[0134] In one or more embodiments, the random access channel opportunity window (855) ends a maximum delay time (850 / 875) after the service stop time (810) or the service start time (860) associated with the target satellite.

[0135] In one or more embodiments, the random access channel opportunity window (855) is allocated to a specific group of user equipment devices including the user equipment (110a / 110b / 110c).

[0136] In one or more embodiments, the access times (815 / 825 / 840) are uniformly distributed random times within the random access channel opportunity window (855).

[0137] In one or more embodiments, the method further comprises determining a determination method for the user equipment (110) to determine an access time (815 / 825 / 840), wherein the determined time is indicated by a system information block (805a).

[0138] In one or more embodiments, the user equipment (110b) determines an access time (840) and sends (820 / 830 / 845) a random access channel preamble (820a / 830a / 845a) in response to no random access channel access failure (835).

[0139] In one or more embodiments, the random access channel opportunity window (855) is delayed based on a time when there are no random access channel access failures (835).

[0140] In one or more embodiments, the random access channel opportunity window (855) includes a plurality of random access channel opportunities for performing random access channel based access.

[0141] In one or more embodiments, at least one random access channel opportunity of the plurality of random access channel opportunities is associated with a user equipment identifier assigned to the user equipment (110a / 110b / 110c).

[0142] In one or more embodiments, a non-transitory computer-readable storage medium comprising computer instructions is provided, which, when executed by a user equipment (110), causes the user equipment (110) to: receive (805) a system information block (805a) from a first network node (112) via a source satellite, wherein the system information block (805a) indicates a random access channel opportunity window (855) in which the user equipment (110a / 110b / 110c) should access the first network node (112) or a second network node. The user equipment (110a / 110b / 110c) is further caused to: determine an access time (815 / 825 / 840) within the random access channel opportunity window (855) based on the system information block (805a). The user equipment (110a / 110b / 110c) is also caused to send (820 / 830 / 845) a random access channel preamble (820a / 830a / 845a) to the first network node (112) or the second network node via the target satellite at the access time (815 / 825 / 840).

[0143] In one or more embodiments, a non-transitory computer-readable storage medium comprising computer instructions is provided, which, when executed by a network node (112), causes the network node (112) to: send (805) a system information block (805a) to a user equipment (110a / 110b / 110c) via a source satellite, wherein the system information block (805a) indicates a random access channel opportunity window (855) during which the user equipment (110a / 110b / 110c) should access the network node (112) or another network node via a target satellite. Additionally or alternatively, the network node (112) may be caused to: receive (820 / 830 / 845) a random access channel preamble (820a / 830a / 845a) from the user equipment (110a / 110b / 110c) via the target satellite at an access time (815 / 825 / 840) within the random access channel opportunity window (855).

[0144] In one or more embodiments, a user equipment (110a / 110b / 110c) is provided, the user equipment comprising: a component for receiving (805) a system information block (805a) from a first network node (112) via a source satellite, wherein the system information block (805a) indicates a random access channel opportunity window (855) in which the user equipment (110a / 110b / 110c) should access the first network node (112) or a second network node. The user equipment (110a / 110b / 110c) further comprises a component for determining an access time (815 / 825 / 840) within the random access channel opportunity window (855) based on the system information block (805a). The user equipment (110a / 110b / 110c) further comprises means for sending (820 / 830 / 845) a random access channel preamble (820a / 830a / 845a) to the first network node (112) or the second network node via the target satellite at an access time (815 / 825 / 840).

[0145] In one or more embodiments, a network node (112) is provided, the network node comprising: means for sending (805) a system information block (805a) to a user equipment (110a / 110b / 110c) via a source satellite, wherein the system information block (805a) indicates a random access channel opportunity window (855) during which the user equipment (110a / 110b / 110c) should access the network node (112) or another network node via a target satellite. Additionally or alternatively, the network node (112) comprises: means for receiving (820 / 830 / 845) a random access channel preamble (820a / 830a / 845a) from the user equipment (110a / 110b / 110c) via the target satellite at an access time (815 / 825 / 840) within the random access channel opportunity window (855).

[0146] Many modifications and other embodiments described herein will occur to those skilled in the art having benefit of the teachings presented in the foregoing description and the associated drawings. Therefore, it should be understood that the present disclosure is not limited to the specific embodiments disclosed, and modifications and other embodiments are intended to be included within the scope of the appended claims.

[0147] In addition, although the above description and related drawings describe example embodiments in the context of certain example combinations of elements and / or functions, it should be understood that alternative embodiments may provide different combinations of elements and / or functions without departing from the scope of the appended claims. In this regard, for example, as described in some of the appended claims, element and function combinations different from the elements and / or functions explicitly described above may also be considered. Although specific terms are used herein, they are used only in a general and descriptive sense and not for the purpose of limitation.

Claims

1. A user equipment, comprising: at least one processor; as well as at least one memory storing instructions, which, when executed by the processor, cause the user equipment to execute: receiving a system information block from a first network node via a source satellite, wherein the system information block indicates a random access channel opportunity window in which the user equipment should access the first network node or a second network node; Determining, based on the system information block, an access time within the random access channel opportunity window; as well as At the access time, a random access channel preamble is sent to the first network node or the second network node via a target satellite.

2. The user equipment of claim 1 , wherein the random access channel opportunity window comprises a maximum delay time during which the user equipment accesses the first network node or the second network node after a satellite switching time, the satellite switching time being one of a service stop time associated with the source satellite or a service start time associated with the target satellite.

3. The user equipment according to claim 2, wherein the random access channel opportunity window starts at a minimum delay time after the satellite switching time.

4. The user equipment according to claim 1, wherein the random access channel opportunity window comprises: A maximum time before a service outage time associated with the source satellite that the user equipment can access the first network node or the second network node.

5. The user equipment of claim 4, wherein the random access channel opportunity window ends at a maximum delay time after the service stop time or the service start time associated with the target satellite. 6 . The user equipment according to claim 1 , wherein the random access channel opportunity window is allocated to a specific user equipment device group including the user equipment.

7. The user equipment according to any one of claims 1 to 6, wherein the access time is a uniformly distributed random time within the random access channel opportunity window.

8. The user equipment according to any one of claims 1 to 6, wherein the access time is determined by a determination method preconfigured by the user equipment.

9. The user equipment according to any one of claims 1 to 8, wherein the user equipment determines the access time and sends the random access channel preamble in response to no random access channel access failure.

10. The user equipment according to claim 9, wherein the random access channel opportunity window is delayed based on the time when there is no random access channel access failure.

11. The user equipment according to claim 1, wherein the random access channel opportunity window comprises: A number of random access channel opportunities for performing random access channel based access.

12. The user equipment of claim 11, wherein at least one random access channel opportunity of the plurality of random access channel opportunities is associated with a user equipment identifier assigned to the user equipment.

13. A network node, comprising: at least one processor; as well as at least one memory storing instructions, which, when executed by the processor, cause the network node to perform at least one of the following: sending a system information block to a user equipment via a source satellite, wherein the system information block indicates a random access channel opportunity window in which the user equipment should access the network node or another network node via a target satellite; as well as A random access channel preamble is received from the user equipment via the target satellite at an access time within the random access channel opportunity window.

14. The network node of claim 13, wherein the random access channel opportunity window comprises a maximum delay time during which the user equipment accesses the network node or the another network node after a satellite switching time, the satellite switching time being one of a service stop time associated with the source satellite or a service start time associated with the target satellite.

15. The network node of claim 14, wherein the random access channel opportunity window starts at a minimum delay time after the satellite switching time.

16. The network node of claim 13, wherein the random access channel opportunity window comprises: A maximum time before a service outage time associated with the source satellite that the user equipment can access the network node or the further network node.

17. The network node of claim 16, wherein the random access channel opportunity window ends a maximum delay time after the service stop time, or a service start time associated with the target satellite.

18. The network node according to any one of claims 13 to 17, wherein the random access channel opportunity window is allocated to a specific user equipment device group including the user equipment.

19. The network node according to any one of claims 13 to 18, wherein the access time is a uniformly distributed random time within the random access channel opportunity window.

20. The network node according to any one of claims 13 to 18, wherein the network node is further caused to: determine a determination method used by the user equipment to determine the access time, wherein the determined time is indicated by the system information block.

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