EP4736475A1

EP4736475A1 - Technologies for non-terrestrial network node switching

Info

Publication number: EP4736475A1
Application number: EP23947905.8A
Authority: EP
Inventors: Fangli Xu; Alexander Sirotkin; Haijing Hu; Ping-Heng Kuo; Sethuraman Gurumoorthy; Ralf ROSSBACH; Peng Cheng; Naveen Kumar R PALLE VENKATA; Yuqin Chen
Original assignee: Apple Inc
Current assignee: Apple Inc
Priority date: 2023-08-07
Filing date: 2023-08-07
Publication date: 2026-05-06
Also published as: KR20260033571A; CN121713500A; WO2025030324A1

Abstract

The present application relates to devices and components including apparatus, systems, and methods for a non-terrestrial network node switching procedures in wireless networks.

Description

TECHNOLOGIES FOR NON-TERRESTRIAL NETWORK NODE SWITCHING

TECHNICAL FIELD

This application relates to the field of wireless networks and, in particular, to technologies for non-terrestrial network node switching.

BACKGROUND

As wireless networks have developed, the networks have developed to service more areas and more remote areas. An approach that has been proposed for the wireless networks to service more areas and more remote areas is the utilization of non-terrestrial networks (NTNs) . In particular, satellites may be utilized within the NTNs to provide radio access network (RAN) service. This may address mobile broadband needs and public safety needs in unserved or underserved areas. NTNs may improve connectivity in a variety of scenarios including, for example, maritime, airplane, and railway scenarios. The use of the satellites within the NTNs presents many challenges.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 illustrates a network arrangement in accordance with some embodiments.
Figure 2 illustrates a signaling diagram in accordance with some embodiments.
Figure 3 illustrates an operational flow/algorithmic structure in accordance with some embodiments.
Figure 4 illustrates a sequence diagram in accordance with some embodiments.
Figure 5 illustrates a satellite information list configuration in accordance with some embodiments.
Figure 6 illustrates another signaling diagram in accordance with some embodiments.
Figure 7 illustrates another signaling diagram in accordance with some embodiments.
Figure 8 illustrates another signaling diagram in accordance with some embodiments.
Figure 9 illustrates another operational flow/algorithmic structure in accordance with some embodiments.
Figure 10 illustrates another operational flow/algorithmic structure in accordance with some embodiments.
Figure 11 illustrates a user equipment in accordance with some embodiments.
Figure 12 illustrates a network device in accordance with some embodiments.

DETAILED DESCRIPTION

The following detailed description refers to the accompanying drawings. The same reference numbers may be used in different drawings to identify the same or similar elements. In the following description, for purposes of explanation and not limitation, specific details are set forth such as particular structures, architectures, interfaces, and techniques in order to provide a thorough understanding of the various aspects of various embodiments. However, it will be apparent to those skilled in the art having the benefit of the present disclosure that the various aspects of the various embodiments may be practiced in other examples that depart from these specific details. In certain instances, descriptions of well-known devices, circuits, and methods are omitted so as not to obscure the description of the various embodiments with unnecessary detail. For the purposes of the present document, the phrases “A/B” and “A or B” mean (A) , (B) , or (A and B) ; the phrase “ (A) B” means (B) or (A and B) , that is, A is optional; and the phrase “based on A” means “based at least in part on A, ” for example, it could be “based solely on A” or it could be “based in part on A. ”
The following is a glossary of terms that may be used in this disclosure.
The term “circuitry” as used herein refers to, is part of, or includes hardware components that are configured to provide the described functionality. The hardware components may include an electronic circuit, a logic circuit, a processor (shared, dedicated, or group) or memory (shared, dedicated, or group) , an application-specific integrated circuit (ASIC) , a field-programmable device (FPD) (e.g., a field-programmable gate array (FPGA) , a programmable logic device (PLD) , a complex PLD (CPLD) , a high-capacity PLD (HCPLD) , a structured ASIC, or a programmable system-on-a-chip (SoC) ) , or a digital signal processor (DSP) . In some embodiments, the circuitry may execute one or more software or firmware programs to provide at least some of the described functionality. The term “circuitry” may also refer to a combination of one or more hardware elements (or a combination of circuits used in an electrical or electronic system) with the program code used to carry out the functionality of that program code. In these embodiments, the combination of hardware elements and program code may be referred to as a particular type of circuitry.
The term “processor circuitry” as used herein refers to, is part of, or includes circuitry capable of sequentially and automatically carrying out a sequence of arithmetic or logical operations, or recording, storing, or transferring digital data. The term “processor circuitry” may refer to an application processor, baseband processor, a central processing unit (CPU) , a graphics processing unit, a single-core processor, a dual-core processor, a triple-core processor, a quad-core processor, or any other device capable of executing or otherwise operating computer-executable instructions, such as program code, software modules, or functional processes.
The term “interface circuitry” as used herein refers to, is part of, or includes circuitry that enables the exchange of information between two or more components or devices. The term “interface circuitry” may refer to one or more hardware interfaces, for example, buses, I/O interfaces, peripheral component interfaces, and network interface cards.
The term “user equipment” or “UE” as used herein refers to a device with radio communication capabilities that may allow a user to access network resources in a communications network. The term “user equipment” or “UE” may be considered synonymous to, and may be referred to as, client, mobile, mobile device, mobile terminal, user terminal, mobile unit, mobile station, mobile user, subscriber, user, remote station, access agent, user agent, receiver, radio equipment, reconfigurable radio equipment, or reconfigurable mobile device. Furthermore, the term “user equipment” or “UE” may include any type of wireless/wired device or any computing device including a wireless communications interface.
The term “computer system” as used herein refers to any type interconnected electronic devices, computer devices, or components thereof. Additionally, the term “computer system” or “system” may refer to various components of a computer that are communicatively coupled with one another. Furthermore, the term “computer system” or “system” may refer to multiple computer devices or multiple computing systems that are communicatively coupled with one another and configured to share computing or networking resources.
The term “resource” as used herein refers to a physical or virtual device, a physical or virtual component within a computing environment, or a physical or virtual component within a particular device, such as computer devices, mechanical devices, memory space, processor/CPU time, processor/CPU usage, processor and accelerator loads, hardware time or usage, electrical power, input/output operations, ports or network sockets, channel/link allocation, throughput, memory usage, storage, network, database and applications, or workload units. A “hardware resource” may refer to compute, storage, or network resources provided by physical hardware elements. A “virtualized resource” may refer to compute, storage, or network resources provided by virtualization infrastructure to an application, device, or system. The term “network resource” or “communication resource” may refer to resources that are accessible by computer devices/systems via a communications network. The term “system resources” may refer to any kind of shared entities to provide services, and may include computing or network resources. System resources may be considered as a set of coherent functions, network data objects or services, accessible through a server where such system resources reside on a single host or multiple hosts and are clearly identifiable.
The term “channel” as used herein refers to any transmission medium, either tangible or intangible, which is used to communicate data or a data stream. The term “channel” may be synonymous with or equivalent to “communications channel, ” “data communications channel, ” “transmission channel, ” “data transmission channel, ” “access channel, ” “data access channel, ” “link, ” “data link, ” “carrier, ” “radio-frequency carrier, ” or any other like term denoting a pathway or medium through which data is communicated. Additionally, the term “link” as used herein refers to a connection between two devices for the purpose of transmitting and receiving information.
The terms “instantiate, ” “instantiation, ” and the like as used herein refer to the creation of an instance. An “instance” also refers to a concrete occurrence of an object, which may occur, for example, during execution of program code.
The term “connected” may mean that two or more elements, at a common communication protocol layer, have an established signaling relationship with one another over a communication channel, link, interface, or reference point.
The term “network element” as used herein refers to physical or virtualized equipment or infrastructure used to provide wired or wireless communication network services. The term “network element” may be considered synonymous to or referred to as a networked computer, networking hardware, network equipment, network node, or a virtualized network function.
The term “information element” refers to a structural element containing one or more fields. The term “field” refers to individual contents of an information element, or a data element that contains content. An information element may include one or more additional information elements.
FIG. 1 illustrates an example network arrangement 100 in accordance with some embodiments. In particular, the network arrangement 100 may employ one or more non-terrestrial components and may, therefore, be referred to as a non-terrestrial network (NTN) .
The network arrangement 100 may include a base station 102. The base station 102 may, in combination with other components within the network arrangement 100, provide radio access network (RAN) services to UEs. The base station 102 may comprise a nodeB. For example, the base station 102 may comprise a next generation nodeB (gNB) , an evolved nodeB (eNB) , or another type of nodeB.
The network arrangement 100 may further include a core network (CN) 104. For example, the CN 104 may comprise a 5^th Generation Core network (5GC) . The CN 104 may be coupled to the base station 102 via a fiber optic or wireless backhaul. The CN 104 may provide functions for the UEs that form a connection with the base station 102, such as subscriber profile information, subscriber location, authentication of services, or switching functions for voice and data sessions.
The network arrangement 100 may further include a UE 106. The UE 106 may be configured to establish a connection with a network and provide services of the network to a user of the UE 106. For example, the UE 106 may be configured to establish a wireless connection to the base station 102.
The network arrangement 100 may further include non-terrestrial nodes, which may also be referred to as “satellites, ” to provide transmission/reception services with respect to the UE 106. The satellites, for example, satellite 1 (SAT_1) 108 and satellite 2 (SAT_2) 110, provide radio access services, through one or more serving cells, for a geographical area 112. The serving cells provided by the satellites 108/110 may generally correspond to a larger area than a cell associated with a terrestrial network. Coverage of one NTN cell may be across multiple jurisdictional boundaries in some embodiments.
The satellites 108/110 may be spaceborne vehicles such as, for example, low-Earth orbit (LEO) satellites, medium-Earth orbit (MEO) satellites, geosynchronous Earth orbit (GEO) satellites, or high-Earth orbit (HEO) satellites. The satellites 108/110 may additionally/alternatively be airborne vehicles such as, for example, high-altitude platform stations (HAPS) or other atmospheric satellites. The satellites 108/110 may proceed along a direction of travel as generally noted in FIG. 1.
The satellites 108/110 may facilitate a wireless connection (or “communication link” ) between the base station 102 and the UE 106 by relaying signals between the two network devices. The signals may be relayed over a first service link between the satellites 108/110 and the base station 102 and a second service link between the satellites 108/110 and the UE 106.
The satellites 108/110 may provide service for the geographical area for consecutive periods of time. The satellite 108 may provide a serving cell at the geographical area 112 for a first period of time, referred to as a service period. As the satellite 108 moves away from the geographical area 112 and satellite 110 moves toward the geographical area 112, service may be switched from satellite 108 to satellite 110. The satellite 110 may then provide a serving cell at the geographical area 112 for a second service period.
The satellites 108/110 may provide services at the geographical area 112 through serving cells having the same configuration or different configurations. For example, in some embodiments, satellite 108 may provide a first serving cell associated with a first physical cell identity (PCI_A) , while the satellite 110 may provide either the first serving cell or a second serving cell associated with a second physical cell identity (PCI_B) . When the satellite switching occurs with unchanged PCI, the replacing satellite simply takes over the service using the previous configuration. For example, the replacing satellite provides the serving cell with the same synchronization signal block (SSB) frequency and same base station (for example, no key change is needed) . Satellite switching without PCI change does not require layer 3 (L3) mobility.
The network arrangement 100 may further include a NTN control center 112. The NTN control center 112 may store ephemeris information regarding the position or the course of satellites within a constellation of satellites. As an example, the NTN control center 112 may store information regarding the position or the course of the satellites 108/110 in the illustrated embodiment. Given the predictable nature of satellite movement and negligible UE mobility in comparison to satellite motion, the network arrangement 100 may be capable of knowing, in advance, the sequence of satellites that are to provide services for the geographical area 112.
FIG. 2 is a signaling diagram 200 illustrating concepts associated with embodiments of the present disclosure.
At 204, the SAT_1 108 may transmit, to the UE 106, RRC signaling that enables satellite switching with an unchanged PCI.
At 208, service may be switched from SAT_1 108 to SAT_2 110. Even though no handover is required in this situation, the UE 106 may still need to acquire ephemeris information with respect to SAT_2 110. Furthermore, since the serving cell is not changed, the UE 106 can only acquire information about the target satellite, e.g., SAT_2 110, from the system information block (SIB) 19 after the satellites switch. Thus, at 212, the UE 106 performs a SIB 19 reacquisition to receive the ephemeris information transmitted in the SIB 19.
Subsequently, the UE 106 may perform a SAT_2 resynchronization at 216. After re-synchronizing with SAT_2 110, data transmissions between the UE 106 and the SAT_2 110 may occur at 220.
In this situation, given that the PCI/frequency/SSB are the same before and after the satellite switch, there may be interference during the switching procedure. Thus, an interruption gap may be needed in which communication to/from the UE 106 is interrupted. Embodiments of the present disclosure describe ways to reduce this interruption. In particular, some embodiments describe the UE 106 acquiring target satellite information for resynchronization before a satellite switching is completed. Additional embodiments describe how to support satellite switching with PCI change in a simple manner that avoids introduction of new SIB/broadcast schemes. Still further embodiments describe support for consecutive satellite switching procedures.
Figure 3 illustrates an operational flow/algorithmic structure 300 in accordance with some embodiments. The operation flow/algorithmic structure 300 may provide a SAT switching procedure that, in some instances, may be performed without L3 mobility. The operation flow/algorithmic structure 300 may be performed or implemented by a UE such as, for example, UE 106 or 1100; or components thereof, for example, baseband processor 1104A.
The operation flow/algorithmic structure 300 may include, at 304, receiving a satellite information list. The satellite information list may include satellite information for one or more target satellites that are to provide future service for a geographical area. The satellite information list may be transmitted via broadcast signaling (for example, in a SIB such as SIB 19 or another SIB) or RRC dedicated signaling.
In some embodiments, the target satellite information for a particular target/neighbor satellite may include satellite information for synchronization purpose (for example, ephemeris information) and timing information related to a satellite switch.
The ephemeris information may be delivered in a plurality of formats including, for example, satellite position and velocity state vectors (hereinafter “state vector format” ) and orbital parameter format. The state vector format may include a first set of information including position information provided as X, Y, Z values (in meters (m) , for example) in the Earth centered, Earth fixed (ECEF) coordinate system; and velocity information provided as velocity in X direction (VX) , velocity in Y direction (VY) , and velocity in Z direction (VZ) (in meters per second (m/s) , for example) in the ECEF coordinate system. The orbital parameter format may include a second set of information including one or more of the following parameters: a semi-major axis (α) in meters; eccentricity (e) ; argument of periapsis (ω) in radians; inclination (i) in radians; longitude of ascending node (Ω) in radians; and mean anomaly (M₀) at epoch time (t₀) in radians. The ephemeris information may be provided in other formats in other embodiments.
The timing information may include: a serving time period in which a particular target satellite is to provide a serving cell with a specific PCI/frequency or at a particular geographic area; or a satellite switching time period. The information regarding the serving time period in which the target satellite is to provide a serving cell with a specific PCI/frequency may not be needed in situations in which the SAT switching procedure is performed with PCI unchanged.
The operation flow/algorithmic structure 300 may further include, at 308, acquiring target satellite information and SAT switching period from the target satellite information list received at 304.
The operation flow/algorithmic structure 300 may further include, at 312, stopping transmissions with a source satellite, e.g, SAT_1 108, during the SAT switching period and starting resynchronization to target satellite, e.g., SAT_2 110, after the SAT switching period.
The operation flow/algorithmic structure 300 may further include, at 316, determining whether the resynchronization with the target satellite is successful. In some embodiments, a failure timer may be used to detect whether resynchronization or satellite switching fails. The failure timer may be started based on the SAT switching period. For example, the failure timer may start at a beginning of the SAT switching period or an end of the SAT switching period.
If the resynchronization is unsuccessful, the operation flow/algorithmic structure 300 may advance to initiating an RRC reestablishment procedure or CHO procedure. The RRC reestablishment procedure may be used to reestablish an RRC connected state with the network. The UE may send an RRC request message to the network and receive, in response, an RRC reestablishment message. Thereafter, the UE may update/derive appropriate keys and communicate with the network on the indicated serving cell.
The CHO procedure may be initiated in embodiments in which it is configured to the UE and the CHO condition is met. In some embodiments, NTN-specific CHO may be configured. The NTN-specific CHO may account for NTN radio characteristics. For example, in NTNs, the variation in signal strength/quality between cell-center and cell edge may not be as pronounced as they are in terrestrial networks.
NTN-specific CHO conditions may be associated with the CHO procedure. For example, time/location-based trigger conditions may be configured together with measurement-based trigger conditions. A time-based trigger condition (condEventT1) may indicate CHO can be executed only between a first time point (T1) and a second time point (T2) . The network may configure T1 (e.g., t1-Threshold) and duration (duration) using a Coordinated Universal Time (UTC) . The location-based trigger condition (condEventD1) may indicate CHO may be executed when the following two conditions are fulfilled: a distance between the UE and a reference location (referenceLocation1) is greater than a distance threshold from the reference location (distanceThreshFromReference1) ; and a distance between the UE and a second reference location (referenceLocation2) is smaller than a distance threshold from the second reference location. An event D1 may be configured as a normal measurement event for a measurement report.
A measurement-based trigger condition may be CHO event A3, A4, or A5. An A3 event may refer to the serving cell being a number of decibels (dB) worse than a target cell. An A4 event may refer to a neighbor cell being better than a threshold. An A5 event may refer to the serving cell being worse than a first threshold and the target cell being better than a second threshold.
In some instances, if a CHO (or radio link/handover) fails, a CHO recovery may be performed. For a candidate cell with condEventT1, a CHO recovery may be executed if timer T2 has not expired. For a candidate cell with condEventD1, a CHO recovery may be executed without checking condEventD1.
If it is determined at 316 that resynchronization is successful, the operation flow/algorithmic structure 300 may advance to determining whether to initiate a RACH in the target cell at 324. This determination may be based on predefined conditions or by network indication as described in further detail herein.
FIG. 4 is a sequence diagram 400 illustrating SAT switching procedure in accordance with some embodiments. The sequence diagram 400 includes a SAT_1 service period 404 in which SAT_1 108 provides service to the geographical area 112. The SAT_1 service period 404 starts at a first time point (serving SAT (SS) start time-T1’) , ends at a second time point (SS stop time-T2’) , and has a duration of SS serving period. The sequence diagram 400 further includes a switching period 408 in which service is switching from SAT_1 108 to SAT_2 112. The switching period 408 starts at a first time point (start-T1) , ends at a second time point (stop-T2) , and has a duration of interruption gap. The sequence diagram 400 further includes a SAT_2 service period 412 in which SAT_2 110 provides service to the geographical area 112. The SAT_2 service period 412 starts at a first time point (target SAT (TS) start time-T1’) , ends at a second time point (TS stop time-T2’) , and has a duration of TS serving period.
In some embodiments, the network may provide the UE 106 with timing information, in the target satellite information list, sufficient for the UE 106 to determine the relevant periods of the sequence diagram 400. The network may provide the target satellite information list to the UE 106 according to one or more of the following options.
In a first option, the network provides SAT switching time (e.g., the switching period 408) as (start-T1, stop-T2) or (start-T1, interruption gap) . Thus, the SAT switching time is defined as [start-T1, stop-T2] , stop-T2 ＞= start-T1, or stop-T2 = start-T1 + interruption gap. The set of values, start-T1, stop-T2 or interruption gap, may be provided per SAT switching event.
In a second option, the network provides the SAT serving time per SAT to UE 106. For example, the SAT’ serving time may be defined as one of the following formats [start time-T1’, stop-time T2’] , [start time-T1′, serving period] , or [stop time-T2, serving period] . The SAT switching time would then be defined as one of the following formats: [SS stop time-T2’, TS start time-T1’] or [SS start time-T1’ + SS serving period, TS start time-T1’]
FIG. 5 illustrates a SAT info list configuration 500 in accordance with some embodiments. The SAT info list configuration 500 may configure the SAT service times to the UE 106 in a manner similar to that described above with respect to the second option.
The SAT info list configuration 500 includes individual configurations for each of a number of satellites. As shown, satellite information is provided for four satellites. Satellite information configuration 504 may provide configuration information for SAT_1 108. As shown, the satellite information configuration 504 may include an identity associated with SAT_1; a frequency at which SAT_1 may provide a serving cell; a PCI of a serving cell provided by SAT_1; NTN-config; and a service time indicator. The service time indicator is shown with a [T1’, T2’] format; however, the same information may be conveyed in a different format as described above, for example.
FIG. 6 is a signaling diagram 600 of a satellite switching procedure in accordance with embodiments of the present disclosure.
At 604, the SAT_1 108 may transmit, to the UE 106, RRC signaling that enables a satellite switching and provides satellite information for SAT_2. The satellite information may include satellite switching or service period information, ephemeris information of the SAT_2 110, etc. The signaling diagram 600 represents a one-shot satellite switching procedure in which a source satellite provides the UE 106 with satellite information corresponding to a target satellite with which the UE 106 is to subsequently connect.
At 608, service may be switched from SAT_1 108 to SAT_2 110. The switch may last a switching period, in which, no data transmissions are performed. The UE 106 may start a failure timer 616 at the beginning of the switching period of the end of the switching period.
Subsequently, the UE 106 may perform a SAT_2 resynchronization at 612. The resynchronization at 612 may be a downlink synchronization in some embodiments. The UE 106 may perform the SAT_2 resynchronization based on the target SAT_2 information provided at 604.
If the resynchronization procedure is successful before the failure timer 616 expires, then data transmissions between the UE 106 and SAT_2 110 may occur at 620.
In some embodiments, after the UE 106 resynchronizes with the SAT_2 110, the UE 106 may determine whether to initiate a RACH in the cell provided by SAT_2 110. In general, a RACH-based SAT switching may be considered more reliable than RACH-less SAT switching, but RACH-based SAT switching may lead to longer interruption time and more RACH resources.
The determination of whether to initiate a RACH may be based on predefined conditions or by network indication. For example, the network may explicitly indicate whether to initiate a RACH procedure for a particular satellite. This indication may be included in the satellite information or separate therefrom. In some embodiments, RACH-less/RACH-based selection may be based on a radio quality. For example, a RACH-less HO may occur when radio quality is above a predetermined threshold. Additionally/alternatively, the RACH-less/RACH-based selection may be based on a UE location change, for example, is a delta distance ＜ threshold, where delta distance represents a change in a location of the UE 106 and threshold is a predetermined threshold. The network may provide an indication of whether the UE 106 is to perform the RACH-less/RACH-based selection and may also provide relevant thresholds.
If the resynchronization procedure is not successful before the failure timer 616 expires, then the UE 106 may transmit an RRC reestablishment message to the network at 624.
FIG. 7 is a signaling diagram 700 of another satellite switching procedure in accordance with embodiments of the present disclosure. The satellite switching procedure of signaling diagram 700 represents a one-shot SAT switching procedure with a fallback to CHO.
At 704, the SAT_1 108 may transmit, to the UE 106, RRC signaling that enables a satellite switching without PCI change. The RRC signaling may also provide satellite information for one or more satellites. As shown, the satellite information includes service time and satellite information for SAT_1 and SAT_2. The service time information for SAT_1 includes [T1, T2] , where T1 corresponds to SS start time-T1’ of FIG. 4 and T2 corresponds to SS stop time-T2’ of FIG. 4. The service time information for SAT_2 includes [T3, T4] , where T3 corresponds to TS start time-T1’ of FIG. 4 and T4 corresponds to TS stop time-T2’ of FIG. 4. The satellite information for each satellite may include NTN-config (for example, ephemeris information, timing advance information, etc. ) and PCI/freq (for PCI-change scenarios) .
At 706, the SAT_1 108 transmits a CHO command to the UE 106. The CHO command may be with respect to a third satellite, for example, SAT_3 708.
At 710, service may be switched from SAT_1 108 to SAT_2 110. The switch may last a switching period, in which, no data transmissions are performed. The switching period may be defined as [T2, T3] .
The UE 106 may start a failure timer at T2 or T3.
The UE 106 may attempt a SAT_2 resynchronization at 712. The UE 106 may perform the SAT_2 resynchronization based on the target SAT_2 information provided at 704.
In some embodiments the UE 106 may determine whether a CHO condition is met upon expiration of the failure timer 716. If the CHO condition is met, the UE 106 may initiate the CHO complete procedure with respect to SAT_3 708.
In other embodiments, the UE may determine whether the CHO condition is met while the failure timer 716 is running. If the CHO condition is met, the UE 106 may initiate the CHO complete procedure with respect to SAT_3 708.
FIG. 8 is a signaling diagram 800 of another satellite switching procedure in accordance with embodiments of the present disclosure. The satellite switching procedure of signaling diagram 800 represents a consecutive SAT switching procedure.
At 804, the SAT_1 108 may transmit, to the UE 106, RRC signaling that enables consecutive SAT switching. The RRC signaling may include a satellite information list for a plurality of satellites including, for example, SAT_1 108, SAT_2 110, SAT_3 808, and SAT_4 812. The satellite information in the list may be presented in the order in which the satellites will provide services for the geographical area 112. The satellite information may include service time information for the various satellites. The service time for SAT_n may be defined as (tn-tn’) , where SAT_n is the satellite providing the service with the indicated PCI/frequency or using the same PCI/frequency. The UE 106 may stop working in the current serving satellite (e.g., SAT_n) at tn’ and perform the resynchronization procedure with a target satellite (e.g., SAT_m) at tm.
The switch period at 814 may last from t1’-t2. After which, the UE 106 may, at 816, perform a SAT_2 resynchronization and data transmission with SAT_2 110.
The switch period at 820 may last from t2’-t3. After which, the UE 106 may, at 824, perform a SAT_3 resynchronization and data transmission with SAT_3 808.
The switch period at 828 may last from t3’-t4. After which, the UE 106 may, at 832, perform a SAT_4 resynchronization and data transmission with SAT_4 812.
Thus, the switching sequence from SAT_1 108 to SAT_2 110 to SAT_3 808 to SAT_4 812 may be known/predicted by the network when the UE 106 is connected with SAT_1 108. The network then provides the UE 106 with data to facilitate a progression of satellite switches in an efficient manner.
Figure 9 illustrates an operational flow/algorithmic structure 900 in accordance with some embodiments. The operation flow/algorithmic structure 900 may be performed or implemented by a UE such as, for example, UE 106 or 1100; or components thereof, for example, baseband processor 1104A
The operation flow/algorithmic structure 900 may include, at 904, establishing a communication link with a network via a first satellite. The network may be an NTN and the first satellite may provide services for a geographical area.
The operation flow/algorithmic structure 900 may further include, at 908, receiving satellite information associated with a second satellite. The satellite information, which may be received in broadcast signaling (e.g., a SIB) or dedicated signaling (e.g., RRC signaling) , may include NTN configuration information for the second satellite (e.g., ephemeris information, timing advance information, etc. ) and timing information associated with service for the geographical area being switched from provided by the first satellite two provided by the second satellite. The timing information may indicate a service period in which the second satellite is to provide services for the geographical area, or a switching period that corresponds to the service switch. The service period may be indicated by transmission of a start time of the service period and a stop time of the service period; a start time of the service period and a length of the service period; or a length of the service period and a stop time of the service period. The switching period may be indicated by transmitting a start time of the switching period and a stop time of the switching period or a length of an interruption gap/switching period.
In some embodiments, the satellite information may include information for the next satellite that is to provide services for the geographical area or for a plurality of satellites that are to provide services for the geographical area over a plurality of consecutive service periods. If information for a plurality of satellites is provided, the information may be ordered in the list according to a sequence of occurrence of the associated service periods.
The operation flow/algorithmic structure 900 may further include, at 912, attempting to resynchronize with the second satellite after a switching period. In some embodiments, a timer may be started at the beginning or end of the switching period. If the resynchronization is not successful before the timer expires, the UE may consider that the race synchronization has failed. Thereafter, the UE may initiate and RRC reestablishment procedure or initiate a CHO procedure if a CHO condition is met.
If the resynchronization is successful, the UE may resume transmissions with the network. In some embodiments, the UE may also determine whether to perform a RACH procedure in the cell provided by the second satellite.
Figure 10 illustrates an operational flow/algorithmic structure 1000 in accordance with some embodiments. The operation flow/algorithmic structure 1000 may be performed or implemented by a base station such as, for example, base station 102 or network device 1200; or components thereof, for example, baseband processor 1204A.
The operation flow/algorithmic structure 1000 may include, at 1004, establishing a communication link with a UE via a first satellite. The network may be an NTN and the first satellite may provide services for a geographical area.
The operation flow/algorithmic structure 1000 may further include, at 1008, transmitting satellite information to the UE. The satellite information, which may be transmitted in broadcast signaling (e.g., a SIB) or dedicated signaling (e.g., RRC signaling) , may include NTN configuration information for the second satellite (e.g., ephemeris information, timing advance information, etc. ) and timing information associated with service for the geographical area being switched from provided by the first satellite two provided by the second satellite. The timing information may indicate a service period in which the second satellite is to provide services for the geographical area, or a switching period that corresponds to the service switch. The service period may be indicated by transmission of a start time of the service period and a stop time of the service period; a start time of the service period and a length of the service period; or a length of the service period and a stop time of the service period. The switching period may be indicated by transmitting a start time of the switching period and a stop time of the switching period or a length of an interruption gap/switching period.
In some embodiments, the satellite information may include information for the next satellite that is to provide services for the geographical area or for a plurality of satellites that are to provide services for the geographical area over a plurality of consecutive service periods. If information for a plurality of satellites is provided, the information may be ordered in the list according to a sequence of occurrence of the associated service periods.
Figure 11 illustrates a UE 1100 in accordance with some embodiments. The UE 1100 may be similar to and substantially interchangeable with UE 106 of Figure 1.
The UE 1100 may be any mobile or non-mobile computing device, such as, for example, mobile phones, computers, tablets, industrial wireless sensors (for example, microphones, carbon dioxide sensors, pressure sensors, humidity sensors, thermometers, motion sensors, accelerometers, laser scanners, fluid level sensors, inventory sensors, electric voltage/current meters, or actuators) , video surveillance/monitoring devices (for example, cameras or video cameras) , wearable devices (for example, a smart watch) , or Internet-of-things devices.
The UE 1100 may include processors 1104, RF interface circuitry 1108, memory/storage 1112, user interface 1116, sensors 1120, driver circuitry 1122, power management integrated circuit (PMIC) 1124, antenna 1126, and battery 1128. The components of the UE 1100 may be implemented as integrated circuits (ICs) , portions thereof, discrete electronic devices, or other modules, logic, hardware, software, firmware, or a combination thereof. The block diagram of Figure 11 is intended to show a high-level view of some of the components of the UE 1100. However, some of the components shown may be omitted, additional components may be present, and different arrangement of the components shown may occur in other implementations.
The components of the UE 1100 may be coupled with various other components over one or more interconnects 1132, which may represent any type of interface, input/output, bus (local, system, or expansion) , transmission line, trace, or optical connection that allows various circuit components (on common or different chips or chipsets) to interact with one another.
The processors 1104 may include processor circuitry such as, for example, baseband processor circuitry (BB) 1104A, central processor unit circuitry (CPU) 1104B, and graphics processor unit circuitry (GPU) 1104C. The processors 1104 may include any type of circuitry or processor circuitry that executes or otherwise operates computer-executable instructions, such as program code, software modules, or functional processes from memory/storage 1112 to cause the UE 1100 to perform satellite switching operations as described herein.
In some embodiments, the baseband processor circuitry 1104A may access a communication protocol stack 1136 in the memory/storage 1112 to communicate over a 3GPP compatible network. In general, the baseband processor circuitry 1104A may access the communication protocol stack 1136 to: perform user plane functions at a PHY layer, MAC layer, RLC layer, PDCP layer, SDAP layer, and PDU layer; and perform control plane functions at a PHY layer, MAC layer, RLC layer, PDCP layer, RRC layer, and a NAS layer. In some embodiments, the PHY layer operations may additionally/alternatively be performed by the components of the RF interface circuitry 1108.
The baseband processor circuitry 1104A may generate or process baseband signals or waveforms that carry information in 3GPP-compatible networks. In some embodiments, the waveforms for NR may be based on cyclic prefix OFDM (CP-OFDM) in the uplink or downlink, and discrete Fourier transform spread OFDM (DFT-S-OFDM) in the uplink.
The memory/storage 1112 may include one or more non-transitory, computer-readable media that includes instructions (for example, communication protocol stack 1136) that may be executed by one or more of the processors 1104 to cause the UE 1100 to perform various operations described herein. The memory/storage 1112 may store satellite information upon which the satellite switching procedures described herein are based.
The memory/storage 1112 includes any type of volatile or non-volatile memory that may be distributed throughout the UE 1100. In some embodiments, some of the memory/storage 1112 may be located on the processors 1104 themselves (for example, L1 and L2 cache) , while other memory/storage 1112 is external to the processors 1104 but accessible thereto via a memory interface. The memory/storage 1112 may include any suitable volatile or non-volatile memory such as, but not limited to, dynamic random access memory (DRAM) , static random access memory (SRAM) , erasable programmable read only memory (EPROM) , electrically erasable programmable read only memory (EEPROM) , Flash memory, solid-state memory, or any other type of memory device technology.
The RF interface circuitry 1108 may include transceiver circuitry and a radio frequency front module (RFEM) that allows the UE 1100 to communicate with other devices over a radio access network. The RF interface circuitry 1108 may include various elements arranged in transmit or receive paths. These elements may include, for example, switches, mixers, amplifiers, filters, synthesizer circuitry, and control circuitry.
In the receive path, the RFEM may receive a radiated signal from an air interface via antenna 1126 and proceed to filter and amplify (with a low-noise amplifier) the signal. The signal may be provided to a receiver of the transceiver that down-converts the RF signal into a baseband signal that is provided to the baseband processor of the processors 1104.
In the transmit path, the transmitter of the transceiver up-converts the baseband signal received from the baseband processor and provides the RF signal to the RFEM. The RFEM may amplify the RF signal through a power amplifier prior to the signal being radiated across the air interface via the antenna 1126.
In various embodiments, the RF interface circuitry 1108 may be configured to transmit/receive signals in a manner compatible with NR access technologies.
The antenna 1126 may include antenna elements to convert electrical signals into radio waves to travel through the air and to convert received radio waves into electrical signals. The antenna elements may be arranged into one or more antenna panels. The antenna 1126 may have antenna panels that are omnidirectional, directional, or a combination thereof to enable beamforming and multiple input, multiple output communications. The antenna 1126 may include microstrip antennas, printed antennas fabricated on the surface of one or more printed circuit boards, patch antennas, or phased array antennas. The antenna 1126 may have one or more panels designed for specific frequency bands including bands in FR1 or FR2.
The user interface 1116 includes various input/output (I/O) devices designed to enable user interaction with the UE 1100. The user interface 1116 includes input device circuitry and output device circuitry. Input device circuitry includes any physical or virtual means for accepting an input including, inter alia, one or more physical or virtual buttons (for example, a reset button) , a physical keyboard, keypad, mouse, touchpad, touchscreen, microphones, scanner, headset, or the like. The output device circuitry includes any physical or virtual means for showing information or otherwise conveying information, such as sensor readings, actuator position (s) , or other like information. Output device circuitry may include any number or combinations of audio or visual display, including, inter alia, one or more simple visual outputs/indicators (for example, binary status indicators such as light emitting diodes (LEDs) and multi-character visual outputs, or more complex outputs such as display devices or touchscreens (for example, liquid crystal displays (LCDs) , LED displays, quantum dot displays, and projectors) , with the output of characters, graphics, multimedia objects, and the like being generated or produced from the operation of the UE 1100.
The sensors 1120 may include devices, modules, or subsystems whose purpose is to detect events or changes in their environment and send the information (sensor data) about the detected events to some other device, module, or subsystem. Examples of such sensors include inertia measurement units comprising accelerometers, gyroscopes, or magnetometers; microelectromechanical systems or nanoelectromechanical systems comprising 3-axis accelerometers, 3-axis gyroscopes, or magnetometers; level sensors; flow sensors; temperature sensors (for example, thermistors) ; pressure sensors; barometric pressure sensors; gravimeters; altimeters; image capture devices (for example, cameras or lensless apertures) ; light detection and ranging sensors; proximity sensors (for example, infrared radiation detector and the like) ; depth sensors; ambient light sensors; ultrasonic transceivers; and microphones or other like audio capture devices.
The driver circuitry 1122 may include software and hardware elements that operate to control particular devices that are embedded in the UE 1100, attached to the UE 1100, or otherwise communicatively coupled with the UE 1100. The driver circuitry 1122 may include individual drivers allowing other components to interact with or control various input/output (I/O) devices that may be present within, or connected to, the UE 1100. For example, driver circuitry 1122 may include a display driver to control and allow access to a display device, a touchscreen driver to control and allow access to a touchscreen interface, sensor drivers to obtain sensor readings of sensors 1120 and control and allow access to sensors 1120, drivers to obtain actuator positions of electro-mechanic components or control and allow access to the electro-mechanic components, a camera driver to control and allow access to an embedded image capture device, audio drivers to control and allow access to one or more audio devices.
The PMIC 1124 may manage power provided to various components of the UE 1100. In particular, with respect to the processors 1104, the PMIC 1124 may control power-source selection, voltage scaling, battery charging, or DC-to-DC conversion.
In some embodiments, the PMIC 1124 may control, or otherwise be part of, various power-saving mechanisms of the UE 1100 including DRX as discussed herein.
A battery 1128 may power the UE 1100, although in some examples the UE 1100 may be mounted deployed in a fixed location, and may have a power supply coupled to an electrical grid. The battery 1128 may be a lithium ion battery, a metal-air battery, such as a zinc-air battery, an aluminum-air battery, a lithium-air battery, and the like. In some implementations, such as in vehicle-based applications, the battery 1128 may be a typical lead-acid automotive battery.
Figure 12 illustrates a network device 1200 in accordance with some embodiments. The network device 1200 may be similar to and substantially interchangeable with base station 102, SAT_1 108, or SAT_2 110 of Figure 1.
The network device 1200 may include processors 1204, RF interface circuitry 1208 (if implemented as a base station) , core network (CN) interface circuitry 1212, memory/storage circuitry 1216, and antenna structure 1226.
The components of the network device 1200 may be coupled with various other components over one or more interconnects 1228.
The processors 1204, RF interface circuitry 1208, memory/storage circuitry 1216 (including communication protocol stack 1210) , antenna structure 1226, and interconnects 1228 may be similar to like-named elements shown and described with respect to Figure 11.
The CN interface circuitry 1212 may provide connectivity to a core network, for example, a 5^th Generation Core network (5GC) using a 5GC-compatible network interface protocol such as carrier Ethernet protocols, or some other suitable protocol. Network connectivity may be provided to/from the base station 1200 via a fiber optic or wireless backhaul. The CN interface circuitry 1212 may include one or more dedicated processors or FPGAs to communicate using one or more of the aforementioned protocols. In some implementations, the CN interface circuitry 1212 may include multiple controllers to provide connectivity to other networks using the same or different protocols.
In some embodiments, the network device 1200 may be a base station and may be coupled with satellites using the antenna structure 1226. In other embodiments, the network device 1200 may be a satellite and may be coupled with the base station using the antenna structure 1226.
It is well understood that the use of personally identifiable information should follow privacy policies and practices that are generally recognized as meeting or exceeding industry or governmental requirements for maintaining the privacy of users. In particular, personally identifiable information data should be managed and handled so as to minimize risks of unintentional or unauthorized access or use, and the nature of authorized use should be clearly indicated to users.
For one or more embodiments, at least one of the components set forth in one or more of the preceding figures may be configured to perform one or more operations, techniques, processes, or methods as set forth in the example section below. For example, the baseband circuitry as described above in connection with one or more of the preceding figures may be configured to operate in accordance with one or more of the examples set forth below. For another example, circuitry associated with a UE, base station, or network element as described above in connection with one or more of the preceding figures may be configured to operate in accordance with one or more of the examples set forth below in the example section.
Examples
In the following sections, further exemplary embodiments are provided.
Example 1 includes a method to be implemented by a user equipment (UE) , the method comprising: establishing a communication link with a network via a first satellite that provides service for a geographical area; receiving, from the network, satellite information associated with a second satellite that is to provide service for the geographical area after the first satellite, the satellite information to include timing information associated with service for the geographical area being switched from provided by the first satellite to provided by the second satellite; and after service for the geographical areas is switched to the second satellite, attempting to re-synchronize the communication link with the second satellite based on the satellite information.
Example 2 includes the method of example 1 or some other example herein, wherein the satellite information includes ephemeris information for the second satellite.
Example 3 includes the method of example 1 or some other example herein, wherein the first satellite is to provide a first cell at the geographical area and the second satellite is to provide a second cell at the geographical area, wherein the timing information comprises a serving time period with a physical cell identity or frequency associated with the second cell.
Example 4 includes the method of example 1 or some other example herein, wherein attempting to re-synchronize the communication link comprises successfully re-synchronizing the communication link and the method further comprises: after successfully re-synchronizing the communication link with the second satellite, determining whether to initiate a random access channel (RACH) procedure in a cell provided by the second satellite.
Example 5 includes the method of example 4 or some other example herein, further comprising: detecting a condition or indication from the network; and determining whether to initiate the RACH procedure in the cell provided by the second satellite based on said detecting the condition or indication from the network.
Example 6 includes the method of example 5 or some other example herein, wherein said detecting a condition or an indication comprises detecting a condition based on a signal quality of the cell provided by the second satellite or a change in location of the UE.
Example 7 includes the method of example 1 or some other example herein, wherein attempting to re-synchronize the communication link comprises unsuccessfully re-synchronizing the communication link and the method further comprises: initiating a radio resource control reestablishment procedure; or determining a conditional handover (CHO) condition is met and initiating a CHO.
Example 8 includes the method of example 1 or some other example herein, further comprising: receiving, from the network before a switching period in which service for the geographical area is switched from being provided by the first satellite to being provided by the second satellite, a CHO command with respect to a third satellite; unsuccessfully re-synchronizing the communication link with the second satellite; and determining a CHO condition is met based on the CHO command and said unsuccessfully re-synchronizing the communication link with the second satellite; and performing a CHO operation with respect to the third satellite based on said determining the CHO condition is met.
Example 9 includes the method of example 1 or some other example herein, further comprising: starting a timer at a beginning or end of the switching period; and determining whether said attempting to resynchronize is successful based on the timer.
Example 10 includes the method of example 1 or some other example herein, wherein receiving the satellite information comprises: receiving the satellite information in a system information block (SIB) or dedicated radio resource control (RRC) signaling.
Example 11 includes the method of example 1 or some other example herein, wherein the timing information comprises: a start time of the switching period; and a stop time of the switching period or a length of an interruption gap.
Example 12 includes the method of example 1 or some other example herein, wherein the timing information is to indicate a service period in which the second satellite is to provide service for the geographical information, wherein the timing information comprises: a start time of the service period and a stop time of the service period; a start time of the service period and a length of the service period; or a length of the service period and a stop time of the service period.
Example 13 includes the method of example 1 or some other example herein, wherein the satellite information is first satellite information and the method further comprises: receiving a list that includes a plurality of satellite information including the first satellite information, wherein the plurality of satellite information respectively corresponds to a plurality of satellites that are to provide consecutive service periods for the geographical area, wherein the plurality of satellite information is ordered in the list according to a sequence of occurrence of the associated service periods.
Example 14 includes a method to be implemented by a base station, the method comprising: establishing a communication link with a user equipment (UE) via a first satellite that provides service for a geographical area; and transmitting, to the UE, satellite information associated with a second satellite that is to provide service for the geographical area after the first satellite, the satellite information to include timing information associated with service for the geographical area being switched from provided by the first satellite to provided by the second satellite.
Example 15 includes the method of example 14 or some other example herein, wherein the first satellite is to provide a first cell at the geographical area and the second satellite is to provide a second cell at the geographical area, wherein the timing information comprises a serving time period with a physical cell identity or frequency associated with the second cell.
Example 16 includes the method of example 14 or some other example herein, further comprising: transmitting, to the UE before a switching period in which service for the geographical area is switched from being provided by the first satellite to being provided by the second satellite, a conditional handover (CHO) command with respect to a third satellite.
Example 17 includes the method of example 14 or some other example herein, further comprising: transmitting the satellite information in a system information block (SIB) or dedicated radio resource control (RRC) signaling.
Example 18 includes the method of example 14, wherein the timing information comprises: a start time of the switching period; and a stop time of the switching period or a length of an interruption gap.
Example 19 includes the method of example 14, wherein the timing information is to indicate a service period in which the second satellite is to provide service for the geographical information, wherein the timing information comprises: a start time of the service period and a stop time of the service period; a start time of the service period and a length of the service period; or a length of the service period and a stop time of the service period.
Example 20 includes the method of example 14, wherein the satellite information is first satellite information and the method further comprises: transmitting a list that includes a plurality of satellite information including the first satellite information, wherein the plurality of satellite information respectively corresponds to a plurality of satellites that are to provide consecutive service periods for the geographical area, wherein the plurality of satellite information is ordered in the list according to a sequence of occurrence of the associated service periods. Another example may include an apparatus comprising means to perform one or more elements of a method described in or related to any of examples 1-20, or any other method or process described herein.
Another example may include one or more non-transitory computer-readable media comprising instructions to cause an electronic device, upon execution of the instructions by one or more processors of the electronic device, to perform one or more elements of a method described in or related to any of examples 1-20, or any other method or process described herein.
Another example may include an apparatus comprising logic, modules, or circuitry to perform one or more elements of a method described in or related to any of examples 1-20, or any other method or process described herein.
Another example may include a method, technique, or process as described in or related to any of examples 1-20, or portions or parts thereof.
Another example may include an apparatus comprising: one or more processors and one or more computer-readable media comprising instructions that, when executed by the one or more processors, cause the one or more processors to perform the method, techniques, or process as described in or related to any of examples 1-20, or portions thereof.
Another example may include a signal as described in or related to any of examples 1-20, or portions or parts thereof.
Another example may include a datagram, information element, packet, frame, segment, PDU, or message as described in or related to any of examples 1-20, or portions or parts thereof, or otherwise described in the present disclosure.
Another example may include a signal encoded with data as described in or related to any of examples 1-20, or portions or parts thereof, or otherwise described in the present disclosure.
Another example may include a signal encoded with a datagram, IE, packet, frame, segment, PDU, or message as described in or related to any of examples 1-20, or portions or parts thereof, or otherwise described in the present disclosure.
Another example may include an electromagnetic signal carrying computer-readable instructions, wherein execution of the computer-readable instructions by one or more processors is to cause the one or more processors to perform the method, techniques, or process as described in or related to any of examples 1-20, or portions thereof.
Another example may include a computer program comprising instructions, wherein execution of the program by a processing element is to cause the processing element to carry out the method, techniques, or process as described in or related to any of examples 1-20, or portions thereof.
Another example may include a signal in a wireless network as shown and described herein.
Another example may include a method of communicating in a wireless network as shown and described herein.
Another example may include a system for providing wireless communication as shown and described herein.
Another example may include a device for providing wireless communication as shown and described herein.
Any of the above-described examples may be combined with any other example (or combination of examples) , unless explicitly stated otherwise. The foregoing description of one or more implementations provides illustration and description, but is not intended to be exhaustive or to limit the scope of embodiments to the precise form disclosed. Modifications and variations are possible in light of the above teachings or may be acquired from practice of various embodiments.
Although the embodiments above have been described in considerable detail, numerous variations and modifications will become apparent to those skilled in the art once the above disclosure is fully appreciated. It is intended that the following claims be interpreted to embrace all such variations and modifications.

Claims

One or more computer-readable media having instructions that, when executed by one or more processors, cause a user equipment (UE) to:

establish a communication link with a network via a first satellite that provides service for a geographical area;

receive, from the network, satellite information associated with a second satellite that is to provide service for the geographical area after the first satellite, the satellite information to include timing information associated with service for the geographical area being switched from provided by the first satellite to provided by the second satellite; and

after service for the geographical areas is switched to the second satellite, attempt to re-synchronize the communication link with the second satellite based on the satellite information.
The one or more computer-readable media of claim 1, wherein the satellite information includes ephemeris information for the second satellite.
The one or more computer-readable media of claim 1 or 2, wherein the first satellite is to provide a first cell at the geographical area and the second satellite is to provide a second cell at the geographical area, wherein the timing information comprises a serving time period with a physical cell identity or frequency associated with the second cell.
The one or more computer-readable media of claim 1 or 2, wherein to attempt to re-synchronize the communication link comprises to successfully resynchronize the communication link and the instructions, when executed, further cause the UE to:

after successfully re-synchronizing the communication link with the second satellite, determine whether to initiate a random access channel (RACH) procedure in a cell provided by the second satellite.
The one or more computer-readable media of claim 4, wherein the instructions, when executed, further cause the UE to:

detect a condition or indication from the network; and

determine whether to initiate the RACH procedure in the cell provided by the second satellite based on detection of the condition or indication from the network.
The one or more computer-readable media of claim 5, wherein to detect a condition or an indication comprises to detect a condition based on a signal quality of the cell provided by the second satellite or a change in location of the UE.
The one or more computer-readable media of claim 1 or 2, wherein to attempt to re-synchronize the communication link comprises to unsuccessfully re-synchronize the communication link and the instructions, when executed, further cause the UE to:

initiate a radio resource control reestablishment procedure; or

determine a conditional handover (CHO) condition is met and initiate a CHO.
The one or more computer-readable media of claim 1 or 2, wherein the instructions, when executed, further cause the UE to:

receive, from the network before a switching period in which service for the geographical area is switched from being provided by the first satellite to being provided by the second satellite, a CHO command with respect to a third satellite;

unsuccessfully re-synchronize the communication link with the second satellite; and

determine a CHO condition is met based on the CHO command and an unsuccessful re-synchronization of the communication link with the second satellite; and

perform a CHO operation with respect to the third satellite based on a determination that the CHO condition is met.
The one or more computer-readable media of claim 1 or 2, wherein the instructions, when executed, further cause the UE to:

start a timer at a beginning or end of the switching period; and

determine whether an attempt to resynchronize is successful based on the timer.
The one or more computer-readable media of claim 1 or 2, wherein to receive the satellite information comprises:

to receive the satellite information in a system information block (SIB) or dedicated radio resource control (RRC) signaling.
The one or more computer-readable media of claim 1 or 2, wherein the timing information comprises:

a start time of the switching period; and

a stop time of the switching period or a length of an interruption gap.
The one or more computer-readable media of claim 1 or 2, wherein the timing information is to indicate a service period in which the second satellite is to provide service for the geographical information, wherein the timing information comprises:

a start time of the service period and a stop time of the service period;

a start time of the service period and a length of the service period; or

a length of the service period and a stop time of the service period.
The one or more computer-readable media of claim 1 or 2, wherein the satellite information is first satellite information and the instructions, when executed, further cause the UE to:

receive a list that includes a plurality of satellite information including the first satellite information, wherein the plurality of satellite information respectively corresponds to a plurality of satellites that are to provide consecutive service periods for the geographical area,

wherein the plurality of satellite information is ordered in the list according to a sequence of occurrence of the associated service periods.
A method to be implemented by a base station, the method comprising:

establishing a communication link with a user equipment (UE) via a first satellite that provides service for a geographical area; and

transmitting, to the UE, satellite information associated with a second satellite that is to provide service for the geographical area after the first satellite, the satellite information to include timing information associated with service for the geographical area being switched from provided by the first satellite to provided by the second satellite.
The method of claim 14, wherein the first satellite is to provide a first cell at the geographical area and the second satellite is to provide a second cell at the geographical area, wherein the timing information comprises a serving time period with a physical cell identity or frequency associated with the second cell.
The method of claim 14 or 15, further comprising:

transmitting, to the UE before a switching period in which service for the geographical area is switched from being provided by the first satellite to being provided by the second satellite, a conditional handover (CHO) command with respect to a third satellite.
The method of claim 14 or 15, further comprising:

transmitting the satellite information in a system information block (SIB) or dedicated radio resource control (RRC) signaling.
The method of claim 14 or 15, wherein the timing information comprises:

a start time of the switching period; and

a stop time of the switching period or a length of an interruption gap.
The method of claim 14 or 15, wherein the timing information is to indicate a service period in which the second satellite is to provide service for the geographical information, wherein the timing information comprises:

a start time of the service period and a stop time of the service period;

a start time of the service period and a length of the service period; or

a length of the service period and a stop time of the service period.
The method of claim 14 or 15, wherein the satellite information is first satellite information and the method further comprises:

transmitting a list that includes a plurality of satellite information including the first satellite information, wherein the plurality of satellite information respectively corresponds to a plurality of satellites that are to provide consecutive service periods for the geographical area,

wherein the plurality of satellite information is ordered in the list according to a sequence of occurrence of the associated service periods.