METHODS, USER EQUIPMENT AND BASE STATION FOR SATELLITE SWITCHING ASSISTANCE INFORMATION USE

Abstract

A UE, connected to a BS using a current cell served by a first satellite, receives information from the BS including assistance information for a cell handover from the current cell to a cell served by a second satellite. The information is received before a stop time indicating when the current cell will no longer serve the UE. The UE performs the cell handover from the current cell to the cell served by the second satellite by using at least the assistance information to find cell synchronization block(s) for the cell served by the second satellite. The BS forwards the information from the BS including the assistance information for a cell handover from the current cell to a cell served by a second satellite. The BS shuts down the current cell at a stop time.

Description

USE OF CELL SWITCH ASSISTANCE INFORMATION FOR SSB SEARCH DURING A SWITCH SATELLITE TECHNICAL FIELD The examples of implementations in this document generally refer to wireless communications and, more specifically, to user equipment (UE) switching between satellites. BACKGROUND A user equipment (UE) is a wireless device, usually mobile, that connects to a cellular network. Modern cellular networks can use satellites to communicate with the UE. Some satellites move relative to the Earth and can create a cell in a specific geographic area, through which the UE can connect to the cellular network. As a satellite moves away from the geographic area, at some point, it will no longer be able to form the cell. Another satellite, moving, for example, in the same direction as the first satellite, can also form the same cell in the same geographic area. As the first satellite moves away and the second satellite takes its place to form the cell, the UE switches between the cell served by the first satellite and the cell served by the second satellite. This cell switching can be problematic. BRIEF SUMMARY This section is intended to include examples and is not intended to be exhaustive. In an illustrative embodiment, a method is disclosed that includes receiving, by a user equipment connected using a current cell served by a first satellite to a base station, information from the base station comprising assistance information for a cell switch from the current cell to a cell served by a second satellite, wherein the information is received before a stop time indicating when the current cell will cease serving the user equipment; and performing, by the user equipment, the cell switch from the current cell to the cell served by the second satellite using at least the assistance information to find one or more cell synchronization blocks for the cell served by the second satellite. A further illustrative embodiment includes a computer program comprising instructions for performing the method of the preceding paragraph, when the computer program is executed on a device. The computer program according to this paragraph is a computer product comprising a computer-readable medium carrying the instructions embedded therein for use with the device. Another example is the computer program according to this paragraph, wherein the program is directly loadable into an internal memory of the device. An illustrative apparatus includes one or more processors and one or more memories that store instructions which, when executed by the one or more processors, cause the apparatus to at least perform the following: receiving, by a user device connected using a current cell served by a first satellite to a base station, information from the base station comprising assistance information for a cell switch from the current cell to a cell served by a second satellite, wherein the information is received before a holding time indicating when the current cell will cease to attend to the user equipment; and perform, by the user equipment, the cell switching from the current cell to the cell served by the second satellite using at least the assistance information to find one or more cell synchronization blocks for the one served by the second satellite. An illustrative software product includes a computer-readable storage medium carrying instructions that, when executed by an apparatus, cause the apparatus to perform at least the following: receive, by a user equipment connected using a current cell served by a first satellite to a base station, information from the base station comprising assistance information for a cell switch from the current cell to a cell served by a second satellite, wherein the information is received before a holding time indicating when the current cell will cease serving the user equipment; and perform, by the user equipment, the cell switch from the current cell to the cell served by the second satellite using at least the assistance information to find one or more cell synchronization blocks for the cell served by the second satellite. In another illustrative embodiment, an apparatus comprises means for: receiving, by a user device connected via a current cell served by a first satellite to a base station, information from the base station comprising assistance information for a cell switch from the current cell to a cell served by a second satellite, wherein the information is received before a holding time indicating when the current cell will cease serving the user device; and performing, by the user device, the cell switch from the current cell to the cell served by the second satellite using at least the assistance information to find one or more cell synchronization blocks for the one served by the second satellite. In an illustrative embodiment, a method is disclosed that includes sending, by a base station to a connected user equipment using a current cell served by a first satellite to the base station, information from the base station comprising assistance information for a cell switch from the current cell to a cell served by a second satellite; and turning off, by the base station, the current cell at a current location at a stop time. A further illustrative embodiment includes a computer program comprising instructions for performing the method of the preceding paragraph, when the computer program is executed on a device. The computer program according to this paragraph is a computer product comprising a computer-readable medium carrying the instructions embedded therein for use with the device. Another example is the computer program according to this paragraph, wherein the program is directly loadable into an internal memory of the device. An illustrative apparatus includes one or more processors and one or more memories that store instructions which, when executed by the one or more processors, cause the apparatus to at least: send, by a base station to a connected user equipment using a current cell served by a first satellite to the base station, information from the base station comprising assistance information for a cell switch from the current cell to a cell served by a second satellite; and turn off, by the base station, the current cell at a current location in a time of 4 2848635 4 of 56 stop. An illustrative software product includes a computer-readable storage medium carrying instructions that, when executed by an apparatus, cause the apparatus to perform at least the following: send, by a base station to a connected user equipment using a current cell served by a first satellite to the base station, information from the base station comprising assistance information for a cell switch from the current cell to a cell served by a second satellite; and turn off, by the base station, the current cell at a current location at a stop time. In another illustrative embodiment, an apparatus comprises means for performing: sending, by a base station to a connected user equipment using a current cell served by a first satellite to the base station, information from the base station comprising assistance information for a cell switch from the current cell to a cell served by a second satellite; and turning off, by the base station, the current cell at a current location at a stop time. BRIEF DESCRIPTION OF THE DRAWINGS In the attached drawings: Figure 1A illustrates the quasi-fixed cell switch to Earth during a satellite switch for a single gNB on Earth; Figure 1B illustrates the quasi-fixed cell switch to Earth during a satellite switch for a gNB that has one CU on Earth and individual DUs on the satellites; Figure 1C illustrates the change from quasi-fixed cell to Earth during a satellite switching for individual gNBs on the satellites; Figure 2 is a flowchart of a method performed by a UE for the use of cell offset information for SSB search during a satellite switchover; Figure 2A illustrates an example of a resource space using frequency offset as flexible cell switching assistance information; Figure 3 is a flowchart of a method implemented by a gNB for using cell offset information for SSB search during a satellite switchover; and Figure 4 is a block diagram of a possible, non-limiting illustrative system in which the illustrative implementations can be put into practice. DETAILED DESCRIPTION OF THE DRAWINGS The abbreviations that may be found in the descriptive report and / or in the figures of the drawings are defined below, at the end of the detailed description section. The word "illustrative" is used herein with the meaning "serving as an example, instance, or illustration." No embodiment described herein as "illustrative" is necessarily to be construed as preferred or advantageous over other embodiments. All embodiments described in this detailed description are illustrative embodiments provided to enable those skilled in the art to manufacture or use the invention and not to limit the scope of the invention as defined by the claims. When more than one acronym, word, or drawing reference number Within this description, it is used with " / ", and in general as used within this description, the 7" can be interpreted as "or", "and", or "both". As used herein, "at least one of the following:<una lista de dos o mas elementos> " and "at least one of<una lista de dos o mas elementos> " and similar nomenclature, where the list of two or more elements is joined by "and" or "or", mean at least any one of the elements, or at least any two or more of the elements, or at least all of the elements. As used herein, the singular forms "a," "an," "the," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It is further understood that the expressions "comprises," "comprising / that comprises," "has," "having / that has," "includes," and / or "including / that includes," when used herein, specify the presence of features, elements, and / or components, etc., set forth, but do not exclude the presence or addition of one or more different features, elements, or components, and / or combinations thereof. Any flowchart (see Figures 2 or 3) or signaling diagram in this document is considered a logic flowchart and illustrates the operation of an illustrative method, the results of executing computer program instructions stored in computer-readable memory, functions performed by logic implemented in hardware, and / or interconnected means to perform functions according to an illustrative embodiment. Block diagrams (such as Figures 1A, 1B, 1C, 4) also illustrate the operation of an illustrative method, the results of executing computer program instructions stored in a 7 2848635 7 of 56 computer-readable memory, functions performed by hardware-implemented logic, and / or interconnected means to perform functions according to an illustrative embodiment. Non-terrestrial communications can complement terrestrial deployments, with satellite connectivity providing coverage beyond the reach of terrestrial deployments. 3GPP has defined and completed a work item for Rel-17 on non-terrestrial networks (NTN) in RP-201256 (see RP-201256, Thales, "Solutions for NR to support non-terrestrial networks (NTN)", 3GPP TSG RAN, Meeting No. 88e, e-meeting, June 29 - July 3, 2020) and a work item for Rel-18 on NTN performance enhancements. One of the objectives for the NTN of NR of Rel-18 is to continue enhancing both NTN-NTN mobility and NTN-TN and service continuity. The work will consider existing NR TN and NTN of NR methods from Rel-17 as a reference for further enhancements, including the following: "Specify the NTN-NTN handover enhancement for the RRC_CONNECTED UEs in the quasi-fixed cell to Earth and the moving cell on Earth to reduce the signaling error. [RAN2, RAN3]". In previous RAN2 meetings, there were some discussions about handover enhancements and some agreements were reached regarding an unchanged PCI solution as follows (shown between opening and closing quotation marks): "Agreements: 2. New proposal 2: RAN2 continues the discussion (for example, in RAN2 No. 120) regarding the solution of maintaining the same PCI after the satellite switchover. Please clarify at least the following: • Impact of RAN1 • The need to perform UL and / or RA beam switching • Applicability to rigid or flexible satellite switching Working assumption: 1. In the case of a cell quasi-fixed to Earth, for the switching of Rigid satellite on the same SSB frequency and the same gNB (no key changes), satellite switching is supported without PCI change (which does not require L3 mobility). Agreements: 1. In the case of a cell quasi-fixed to Earth, for the switching of "Simplified satellite on the same SSB frequency and the same gNB (no key changes), satellite switching is supported without PCI change (which does not require L3 mobility), unless major technical issues are identified by RAN1 (as usual, RAN2 will aim to minimize the impact of the specification so that it fits within Rel-18)" In the NTN of Rel-17, cells originating from different satellites are associated with different PCIs. A stationary UE will therefore experience continuous L3 mobility as the serving satellite moves out of coverage and a new satellite takes over coverage of the geographic area. The unchanged PCI technique was introduced to avoid the need for L3 mobility, which can reduce signaling overhead considering the large number of UEs served within an NTN cell. It should be noted that the examples in this document may work with the PCI techniques unchanged or with changed PCI techniques. Turning to Figure 1A, this figure illustrates the switch from a quasi-fixed cell to Earth 120 during a satellite switch for a single gNB on Earth. Satellites 110-1 and 2110-2 are moving in the corresponding 111-1 and 111-2 directions, meaning that satellite 110-1 is moving out of range of cell 120, so satellite 2110-2 takes over cell 120. That is, UE 10 will switch from satellite 110-1 to satellite 2110-2. Satellite 1110-1 communicates with GW 90-1 and gNB 70-1 via parabolic antenna 160 and link 140, where gNB 70-1 uses antenna 150. Link 140 can be wired or wireless. In this example, satellite 1110-1 acts as a repeater, and there is a path 130-1 from GW 90-1 to UE 10. That is, satellite 1110-1 repeats communications on link 130-1a to or from UE 10 via link 130-1b, and path 130-1 comprises both links 130-1a and 130-1b. Similarly, satellite 2 1102 communicates with GW 90-1 and gNB 70-1 via parabolic antenna 160 and link 140. Satellite 2 110-2 in this example acts as a repeater, and there is a path 130-2 from GW 90-1 to UE 10. That is, satellite 2 110-2 repeats communications on link 130-2a to or from UE 10 via link 130-2b, and path 130-2 comprises both links 130-2a and 130-2b. Cell 120 corresponds to geographic area 121. Although a "cell" 120 is illustrated, slight differences in cell location are shown: cell 120-1 is an "old" (or current) cell formed by satellite 1 110-1; and cell 120-2 is a "new" one formed by satellite 2 110-2. As shown in Figure 1A, for the quasi-fixed-to-Earth cell scenario, if an unchanged PCI concept were used, this is based on a geographic area 121 that is associated with a PCI 170 and a gNB 70-1. A gNB 70-1 could provide service to the same coverage area while connecting to different satellites 110-1, 110-2, and the PCI 170 remains unchanged after the satellite switchover. Because the PCI 170 and the service gNB 70-1 configuration remain the same, the satellite switchover can be largely transparent to the UE 10. The following stages will take place during the satellite switching (see Figure 1A): 1. The UE 10, which is stationary or in motion, is being served by satellite-1 110-1. 2. As satellite-1 110-1 moves away from UE 10 and approaches the Satellite-2 110-2, the gNB 70-1 (which routes service cell 120-1 through satellite-1 110-1) can indicate when satellite-1 110-1 will be turned off, when satellite-2 110-2 will be available and how to perform resynchronization with the new cell. 3. Once satellite-2 110-2 takes over (cell 120-2, which (takes over cell 120-1), the UE performs DL / UL synchronization operations to resume TX / RX. As mentioned previously, even though UE 10 is being served by a new satellite, the UE does not change the service gNB, so the UE can maintain the cell configuration. Satellite 1 110-1 and satellite 2 110-2 are configured with the same PCI 170 (in this example), the same UE context, and the same protocol stack (including, for example, SSB generation, encoding / decoding, modulation / demodulation, same CORESET configuration, and switching routing). However, based on the UE reference, satellite-1 110-1 and satellite-2 110-2 introduce different frequency drifts (i.e., Doppler) and timing. Note that specific agreements have not yet been reached regarding how UE and NW should behave in the event of satellite switching as part of the 3GPP discussions. The conditions for the PCI mechanism to function without changes include the following: a) NTN cells must be deployed as quasi-fixed cells to the Earth (EFC) because the cell coverage area must not change; b) The network (NW) should indicate to the UE how / when to perform DL and UL synchronization after the satellite switchover; and c) The network accepts an interruption gap so that the UE can detect the new timing and adapt to it. The network needs to have a means to prevent a radio link failure (RLF) during this interruption gap (i.e., after the "old" / "current" cell disappears and before the "new" cell takes over). In Rel-18, the focus is on transparent architecture, and the most obvious case is when the cells are provided by the same gNB; that is, the same cell with the fixed PCI is provided by the same gNB, so only the satellite node changes. However, theoretically, this could also work with different gNBs and potentially even for the regenerative case. That is, in addition to the structure of figure 1A, where the gNB 70 is On Earth, other structures are possible. Turning to Figure 1B, this figure illustrates the quasi-fixed cell switch to Earth during a satellite switchover for a gNB that has a CU on Earth and individual DUs on the satellites. In the example in Figure 1B, the gNB 70-2 is divided into a central unit (CU) 150-1 on Earth and individual distributed units (DUs): DU 150-2a on satellite 110-1; and DU 150-2b on satellite 2110-2. This example requires additional coordination (relative to the structure in Figure 1A) between the gNB-CU 150-1 and the gNB-DUs 150-2a and 150-2b, because there is communication between the CU and the DU to establish coordination. Figure 1C illustrates another possibility for quasi-fixed cell switching to Earth during a satellite switchover for individual gNBs on the satellites. This example has the gNB 70s deployed on the satellites: gNB 1 70-1 is deployed on satellite 1 110-2; and gNB 2 70-2 is deployed on satellite 2 110-2. In this scenario, a relatively high degree of coordination between the gNBs would be necessary, compared to the coordination required in Figure 1B. Figure 1C illustrates the regenerative case, where the 110 satellites regenerate the information being transmitted by GW 90-1. Furthermore, a similar concept for changed PCI and unchanged PCI was discussed in R2-2306517 (see R2-2306517, Sequans Communications, "'Unchanged PCI' solution vs 'PCI change only' solution", 3GPP TSG-RAN WG2 Meeting No. 122, Incheon, South Korea, May 22-26, 2023), which can resolve the issue of unchanged PCI not being supported by Rel. 17 terminals. Therefore, some of the problems with unchanged PCI may also exist for changed PCI. In other words, the changed PCI technique is a workaround to avoid impacting Rel. 17 UEs. The operating principle is the same (without L3 mobility), but the new cell should use a different PCI. As previously explained, the examples in this document are valid for both changed PCI and unchanged PCI scenarios. That is, regardless of whether the PCI changes or not, the UE still requires certain support information to know when and how to perform the cell switchover, and the examples in this document can provide that support information. The following agreements were reached during RAN2 Meeting No. 121-bis-e and RAN2 Meeting No. 122 on the topic of PCI without changes. At RAN2 meetings No. 121-bis-e and RAN2 No. 122, the following agreements were reached on the subject (both are enclosed in opening and closing quotation marks): "Agreements in RAN2 No. 121-bis-e 1. In the case of a quasi-fixed cell to Earth, for rigid satellite switching on the same SSB frequency and the same gNB (without key changes), satellite switching without PCI change (which does not require L3 mobility) is supported, unless major technical problems are identified by RAN1 (as usual, RAN2 will aim to minimize the impact of the specification so that it fits within Rel-18) 2. Remove the parenthetical phrase "as usual, RAN2 will aim to minimize the impact of the specification so that it fits within Rel-18" in the LS to RAN1. The action to RAN1 will also request feedback for rigid satellite switching (not just the flexible satellite switching case), for example, the action to RAN1 is to see if There is a major technical problem (as in the agreement). "Agreements in RAN2 No. 122 The service-t in SIB19 can also be interpreted by the Rel-18 UE in Connected mode to know that a satellite change or a connection link change is taking place. In the PCI scenario without hard-switching changes (i.e., no handover), the UE needs to know the moment when the UE attempts resynchronization. (It remains for further study whether a new "start-t" / gap-t is needed or whether service-t can be reused (i.e., no other IE) if the gap is very short / zero). This means that it was agreed to support at least rigid satellite switching with unchanged PCI and without L3 mobility. However, explicit details have not yet been decided. Furthermore, in RAN1 No. 113, the following LS was addressed (R1-2304323, "LS on unchanged PC", RAN of 3GPP TSG WG1 No. 113, Incheon, Korea, May 22 - May 26, 2023) (this is in opening and closing quotation marks): "For the enhancement of mobility in the NTN of NR of Rel-18, in the case of quasi-fixed cell to the Earth, RAN2 has analyzed a PCI scenario without changes, which includes rigid satellite switching (non-overlapping satellite coverage at switching time) and flexible satellite switching (overlapping satellite coverage at switching time). RAN2 has agreed that, in the case of a quasi-fixed cell to Earth, for rigid satellite switching on the same SSB frequency and the same gNB (without key changes), satellite switching without PCI change (which does not require L3 mobility) is supported, unless problems are identified. Important technical aspects by RAN1. RAN2 understands that the conventional impact includes being able to notify the UE to reacquire DL / UL synchronization with the service cell after the satellite switchover. RAN2 understands that the feasibility of flexible satellite switching without PCI change (without requiring L3 mobility) is more relevant to RAN1's ​​aspects, and would like to check its feasibility with RAN1. ACTION: RAN2 kindly requests RAN1 to consider the above agreement regarding rigid satellite switching without PCI change and provide feedback if RAN1 identifies any significant technical issues, and also provide that feedback regarding the feasibility of supporting flexible satellite switching without PCI change. During RAN1 No. 113, the topic was discussed briefly and RAN1 provided an LS response to RAN2 in R1-2306210 which has the following information (mainly addressing hard switching) (with this section in opening and closing quotation marks): "Question 1: ^For rigid satellite switching without PCI change, what if RAN1 identifies any major technical issues?" Answer: RAN1 analyzed UE resynchronization when hard-switching, because new common cell-specific TA, K_mac, ephemeris and K-offset are applied during resynchronization with a new satellite. From RAN1's ​​perspective, no feasibility issues are identified for rigid satellite switching without PCI change. During the RAN1 discussions regarding the LS response, there was no consensus on the response in flexible satellite switching. It is expected that such discussions will continue in RAN1 No. 114 in August 2023. In the unchanged PCI scenario, satellite switching occurs transparently for the UE. This means that the UE switches from a source satellite access node to a destination satellite access node without performing Layer 3 mobility and without changing the service gNB. Under the flexible satellite switching scenario, the intention is for the same geographic area to be served by two satellites simultaneously, possibly with the same physical cell ID (PCI 170). Another possibility is that the incoming satellite cell becomes available before the outgoing satellite cell is deactivated. Therefore, the intention is that the two cells (e.g., created with the same PCI) must be non-separable by the UE (to create the illusion of being in the "same cell served by the same gNB"), while also allowing the UE to perform a controlled "switch." At RAN1 Meeting No. 113, there was no concrete information regarding how flexible satellite switching was intended to work. For example, instructing the UE to resynchronize with its current PCI (i.e., current service cell) did not guarantee that the UE would find a set of SSBs different from its current one. When performing a flexible switch from an "old cell" to a "new cell," the UE, as part of the "resynchronization," would have the same probability of finding the old cell as it would of finding the new cell (with the same PCI). While attempting to access the new cell, the UE risks: a) find the "old cell" (i.e., the same SSB location), which means the UE will attempt to resynchronize with the outgoing satellite. This could driving the UE to RLF and legacy RRC reset, which increases UE power consumption, reduces system capacity, and degrades the user experience. b) Search for a long time for the "new cell" (i.e., SSB from the same service gNB but in a different location). c) Even when the new cell is found, the UE needs to know which SSB belongs to the old cell and which SSB belongs to the new cell, because, for example, the satellite assistance information is different. The examples in this document address these and other problems. One example proposes providing "cell switching assistance" information that allows a UE to perform a "guided search" to the same cell PCI (the unchanged PCI scenario) when UE 10 is requested to resynchronize with cell 120 as part of the NTN operation. The cell switching must take place without L3 mobility (i.e., without handover), and the UE should resynchronize only with the cell routed through the incoming satellite. The same "guided search" can also be applied to the changed PCI scenario, where the PCI for old and new cells is different. More specifically, flexible cell switching support information (also called support information for a flexible cell switching) may include a set of one or more of the following elements: 1) A time offset relative to the existing cell timing (i.e., instructing the UE to search for a new SSB after an offset of 'X' slots). Such an offset could use, For reference, the first OFDM symbol after the last SSB reading. Alternatively, the indication could include the absolute time at which the UE should begin measuring. 2) A frequency offset of the SSBs to be used for synchronization (indicated either as an absolute offset or as a relative offset with respect to the existing Point A (also "Point A"), described below, for the "old cell"). 3) A different set of SSB locations can be provided to the new cell. This can be done by reusing the same IE or a similar one to that already available in 3GPP TS 38.331 (SSB-ToMeasure - potentially with an indication that the SS / PBCH block is an SSB with the same PCI as the current service cell). See, for example, 3GPP TS 38.331 V17.5.0 (06-2023). The bitmap in this IE will indicate specific SSB indices, which are provided by the outgoing and incoming satellites. 4) A time interval (e.g., a window) for the UE to perform the search for a resynchronization attempt. 5) Ephemeris information to apply when attempting a resynchronization, which the UE can use to deduce at least the time offset, on the condition that the timing on the gNB (or reference point) is identical. All information may have a timestamp, since displacements can change (at least over time) due to satellite movement. For the timestamp, there could be a single timestamp for any of the points (1)-(5) above. use, but each of the elements may come with a corresponding time indication for individual elements. Because most cell characteristics (i.e., cell configuration parameters) will remain the same during a configured flexible switching of the service satellite, it could be assumed that the overall cell configuration (and the UE-specific configuration) will remain unchanged. That is, the system bandwidth, CSI-RS configuration, CORESET configuration, and UL and PUCCH bandwidth configurations would remain unaltered.From the point of view of system operation, it would mainly be the time-frequency location of the SSBs that would change (and, of course, also the associated transmission timing relationships caused by the change in connection link and service link delays, as well as the Doppler shift change caused by the service link change - all of these would be associated with the ephemeris information that is also assumed to be available to the UE before the resynchronization attempt). It should be noted that, although the examples describe operation under NTN (where the examples utilize the fact that a gNB 70 can potentially serve the UE through multiple "remote radio entry units"—the satellites), the examples can be extended to also cover cases where a UE is capable of autonomously determining its own position in the network, as well as the positions of the gNB(s). For such cases, in principle, it would also be possible to perform "PCI switching" without involving L3 handover mechanisms. However, such an extension to terrestrial network operation could be complex. As part of the operation, the UE should recognize the frame structure as described in 3GPP TS 38.211, see, for example, 3GPP TS 38.331 V17.5.0 (06-2023), where an essential part for Point A is quoted below (in opening and closing quotation marks): "Point A serves as a common reference point for the resource block grids and is obtained from: - offsetToPointA for a downlink from CellP where offsetToPointA represents the frequency offset between point A and the lowest subcarrier of the lowest resource block, which overlaps with the SS / PBCH block used by the UE for initial cell selection, expressed in resource block units assuming a subcarrier separation of 15 kHz for FR1 and a subcarrier separation of 60 kHz for FR2; - for operation without shared spectrum channel access in FR1 and FR2-1, the lowest resource block has the subcarrier spacing provided by the upper layer parameter subCarrierSpacingCommon; - for operation with shared spectrum channel access in FR1 or FR2, and for operation without shared spectrum channel access in FR2-2, the lowest resource block has the same subcarrier spacing as the SS / PBCH block used by the UE for initial cell selection; - absoluteFrequencyPointA for all other cases where absoluteFrequencyPointA represents the frequency location of point A expressed as in ARFCN". As can be seen, Point A is being described as an offset from the SSB to the lower PRB of the system bandwidth. For the situation described above, timing offsets relative to the existing SSB structure would be relatively trivial, whereas modifications to the offset of Point A would potentially require some additional consideration. As suggested in the examples, UE 10 might be configured with an additional value (e.g., delta-offsetToPointA) to be applied during resynchronization. This ensures that a UE performing such an operation would not encounter a "current SSB" because the "new SSB" is located on a different set of subcarriers. The intention behind delta-offsetToPointA is to place the new SSB at a different frequency (compared to the current SSB) within the overall bandwidth system. The time offset could be optional, but some orthogonality across the frequency domain is useful. The details presented above are described below through an example. This example uses part of Figure 1A and also Figure 2, which is a flowchart of a method implemented by a UE for using cell offset information for SSB search during a satellite switchover. In the example in Figure 1A, UE 10 is currently connected to satellite 1110 as its "old" (i.e., current) satellite. This satellite 1 110-1 is also an outgoing satellite, because it is moving away (according to the 111-1 direction) from cell 120. On the other hand, satellite 2 110-2 is an incoming satellite (via the 111-2 direction) that will take over the formation of cell 120. Both satellites 110-1 and 110-2 therefore form, cell 120 to which UE 10 is or will be connected. The outgoing and incoming satellites will route the same 120 cell (originating from the same gNB 70-1). This means that, for flexible satellite switching, during an overlap period (when both 110 satellites form the same 120 cell), UE 10 is connected to the 120-1 service cell (formed by the outgoing 110-1 satellite) and needs to resynchronize with the incoming 110-2 satellite and its corresponding 120-2 cell. Because it is the same cell configuration for both satellites, the SSB time and frequency location will also be the same for both. The UE requires support information so that it knows where to search for / measure the new cell. Otherwise, the risk is that the UE will measure the SSB again from the current (e.g., old) 120-1 cell and resynchronize (undergo resynchronization) with the outgoing 110-1 satellite. In preparation for and prior to flexible cell switching (e.g., and satellite), gNB 70-1 sends flexible cell switching assistance information 230, which is received by UE 10 in block 205 of Figure 1A. This flexible cell switching assistance information 230 is shown as 230-1 to 230-5 and is described below. Additionally, UE 10 can determine a stop time in block 203, indicating when the current cell (e.g., service cell) will cease servicing the UE. Therefore, block 205 is executed before the stop time. The stop time can be determined by explicit signaling and the corresponding reception of a stop time indication, or by using, for example, the service-t, start-t, or gap-t described below. In other words, UE 10 can determine a time at which The current cell will stop serving the UE, and this specified time is the downtime. In block 210, UE 10 uses the "old" (current, for example, service) cell 120-1 (from the outgoing satellite 110-1). In block 215, UE 10 determines whether a flexible satellite switch to the "new" cell 120-3 (formed by the second incoming satellite) should take place. The UE can determine when to perform the switch in a variety of ways. In RAN2 No. 122, it was agreed that the UE can interpret service-t to know that a satellite switch will take place (but nothing more specific was agreed upon). However, there are ongoing discussions about whether the gNB should indicate when the new cell will become available (start-t) or how long the overlap gap (also called the interrupt gap) (gap-t) should be. In other words, the stop time determined in block 203 can be determined using these techniques, or through others.Regardless of the actual usage, UE 10 can determine in block 215 whether or not a flexible satellite switch to the "new" cell 120-3 should be performed. If not (block 215 = No), the UE uses the old cell. If so (block 215 = Yes^), the UE performs (reference 218) the cell switch, which includes blocks 220 and 225. Note that cell 120 can be comprised of satellite 110 or the BS, for example, gNB 70; in this case, satellite 110 only retransmits the signals. Therefore, the term "served" is used herein to indicate that cell 120 is made up of satellite 110 itself or satellite 110 relaying signals from a gNB 70. Specifically, the UE searches (block 220) for the synchronization block(s) of the "new" cell 120-2 from the incoming satellite 110-2. Block 220 has multiple sections 1-5, each of which corresponds to flexible cell switching assistance information 230-1 to 230-5. Note that flexible cell switching assistance information 230-1 to 230-5 corresponds to the flexible cell switching assistance information (1) to (5) described above, and this information may be described as assistance information for a flexible cell switching. In block 220-1, the UE performs a search using the flexible cell switching assistance information 230-1 of the time offset(s) relative to the cell timing. The SSB can move in frequency and time. One idea of ​​(1) (230-1) is to indicate a time offset, or multiple time offsets, so that the UE knows at what instant or instants it should measure for the SSB coming from the incoming satellite. In block 220-2, the UE performs a search using the flexible cell switching assistance information 230-2 for a frequency offset. This can be considered a similar concept to that in (1) (2302), but the offset is in the frequency domain. The UE is given a specific offset so that it knows the frequency at which the new SSB is located. Note that this assumes a certain orthogonality between the old and new SSBs. The frequency offset of the SSB(s) is used for the detection, measurement, and evaluation of the SSB(s) in the cell served by the incoming satellite (e.g., the second satellite). As previously described, the UE 10 can be configured with an additional value (e.g., delta-offsetToPointA) to be applied during the Resynchronization is performed in such a way that it is ensured that a UE performing this operation would not find a "current SSB" because the "new SSB" is located on a different set of subcarriers. An example of block 220-2 is block 220-2i, where the UE uses flexible cell switching assistance information 230-2i to search for the additional value (e.g., delta-offsetToPointA). Turning to Figure 2A, this figure illustrates an example of a 270 resource space using frequency offset as flexible cell switching assistance information. The 270 resource space is a time space (in symbols, e.g., OFDM symbols) and a frequency space (in subcarriers). A symbol offset of 255 in time is between cell synchronization blocks (e.g., SS / PBCH) 280-1 and 280-2 and also between cell synchronization blocks (e.g., SS / PBCH) 280-3 and 280-4. Each SS / PBCH block, as an example of a 280 cell synchronization block, has synchronization (sync) signals (SS, such as PSS, SSS) and a PBCH, which is a set of time-frequency resources surrounding an internal synchronization signal.The offsetToPointA 250 shows a frequency shift from a lower frequency (e.g., the lowest subcarrier of the lowest resource block) for resource space 270 to a first subcarrier for SS / PBCH blocks 280-1 and 280-2. The frequency shift 260, for example, as delta-offsetToPointA, illustrates a shift from offsetToPointA to the first subcarrier for SS / PBCH blocks 280-3 and 280-4. SS / PBCH blocks 280 in region 290 are used for the old cell 120-1, while SS / PBCH blocks (as synchronization blocks) are used for other purposes. (of cell) 280 in region 295 are used for the new cell 120-2. Therefore, delta-offsetToPointA (along with offsetToPointA), or another indicator of a start subcarrier, can be used to indicate where the SS / PBCH 280 blocks are in region 295. Cell 280 synchronization blocks, in one example, are SS / PBCH blocks. Cell 280 synchronization blocks may also be referred to as SSBs, because SSBs contain SS / PBCH blocks and are typically not separable. It should be noted that time offsets could be applied similarly (see block 220-1). For example, reference 286 indicates a possible time offset from time 285 (the start of block SS / PBCH 280-1) where the start symbol of block SS / PBCH 280-3 could be at reference 287 and indicated by block SS / PBCH 280-3a. Note that both blocks SS / PBCH 280-3 and 280-4 would be shifted to the right by the time offset indicated by reference 286 and from blocks SS / PBCH 280-3a and 280-4a. In block 220-3 of Figure 2, the UE performs a search using flexible cell switching assistance information 230-3 from a different set of SSB location information (e.g., time / frequency). More specifically, as part of the SSB configuration, the UE may receive the SSB-ToMeasure IE indicating an SSB time / frequency pattern (e.g., possibly including indices for consecutive SSBs, where this is most relevant for beam-based mobility management). In this case, the intention is for the UE to receive a new SSB-ToMeasure IE so that it knows where / when to measure the new SSB. In block 220-4, the UE performs a search using flexible cell switching assistance information 230-4 for a specific search time window. This may involve a similar principle to the previous options, but the UE is only instructed to search from, for example, -T to T. In this case, gNB 70-1 should ensure that, during this time window, the UE would find only the SSB routed from the incoming satellite 110-2. For the example in Figure 2A of SS / PBCH blocks 280-3a and 280-4a, the time period for these blocks is different and does not overlap with SS / PBCH blocks 280-1 and 280-2, and would be a good candidate for blocks 220-4 / 230-4. In block 220-5, the UE performs a lookup using the flexible cell switching assistance information 230-5 from the ephemeris information. An example of a problem with this L3-non-mobility satellite switching is that the frequency and timing drift will change from one satellite to another. In NTN, the UE has knowledge of the satellite ephemeris and the common TA (i.e., the gNB-to-satellite RTT) such that the UE can precompensate for the Doppler shift and timing drift due to the satellite's speed. When switching from one satellite to another, the UE might need such assistance information (provided by ephemeris information) to estimate the new Doppler effect and the new RTT, so that the UE can better discriminate than without this information as to when and where the new SSB occurs. In block 225, the UE uses the "new" cell. It is noted (see block 228) that cell switching can be performed using a change PCI between cells (i.e., the current cell and the new cell use different PCIs) or the same PCI for both cells. It should also be noted that a multitude of options 220-1 through 220-5 can be used. For example, both blocks 220-1 and 220-2 (and 220-2i) can be used together, because the 280 cell synchronization blocks can be shifted in both time (220-2) and frequency (220-2 and 220-2i). Another example is using the time interval information in 220-4 while also applying the frequency shift information in 220-2 or 220-2i. A further example is that block 220-5 can be combined with any of blocks 220-1 through 220-4. Referring to Figure 3, this figure is a flowchart of a method implemented by a gNB for using cell offset information for SSB search during a satellite switchover. In block 305, gNB 70 sends flexible cell switchover assistance information 230 to UE 10. gNB 70 in block 310 communicates, if necessary, with another gNB so that the other gNB has the information to send cell synchronization block(s) 280 to the correct location(s) according to the flexible cell switchover assistance information. In the case of a transparent architecture such as in Figure 1A, there is generally no communication between the two 110 satellites. In the case of a regenerative architecture such as in Figure 1C, there could be coordination between the gNB functions on board the 110 satellites.That is, the gNB 70-1 on satellite 1 110-1 communicates information with the gNB 70-2 on satellite 2 110-1 in such a way that the gNB 70-2 sends the cell synchronization block(s) 280 in the correct location(s) according to the support information. flexible cell switching. In block 315, the gNB 70 determines whether a flexible switch to a new satellite should be performed. If not (block 315 = No), the gNB 70 waits. If a flexible cell switchover is to be performed (block 315 = SQ), block 320 is executed, where gNB 70 determines whether the new cell is controlled exclusively by the gNB. If so (block 320 = S), gNB 70 in block 325 sends the cell synchronization block(s) to the correct location(s) according to the flexible cell switchover support information. If not (block 320 = No), gNB 70 communicates in block 330 with the other gNB (e.g., 70-2 in Figure 2C) so that the other gNB can determine whether to send the cell synchronization block(s) to the new cell.Note that block 330 is one option (Option 1), and an alternative option (block 331, Option 2) is that one core network element can inform the other gNB when and how to send the cell synchronization block(s) in the new cell. This procedure involves the source gNB, the destination gNB, and the core network (CN), because some mobility and upper-layer management reside in the CN, while some content and context are transferred from the source gNB to the destination gNB (this can be done through the CN or directly). It should also be noted that the two gNB 70s could be prepared (for example, using gNB-to-gNB communication or communication from one core network element to both gNB 70s) in advance with a time instance(s) indicating, for example, when the soft cell switchover will take place.In block 335, the gNB 70 turns off the original cell (e.g., at stop time) at the current location (e.g., because the cell can. reappear in a different location). Turning to Figure 4, this figure shows a block diagram of a possible, non-limiting example of a cellular network 1 connected to a user equipment (UE) 10. Multiple network elements are shown in the cellular network in Figure 4: a base station 70; and a backbone network 90. ​​In this example, the base station 70 is a gNB (for example, or another access node that provides access via UE 10 to the backbone network 90). The gateway (GW) is part of the backbone network 90 and therefore also uses the reference number 90 (as 90-1). As illustrated in Figure 1A, satellite 110 can act as a "repeater" and be part of cellular network 1, and in particular, part of RAN 420, which includes gNB 70. Satellite 110 includes circuitry 410, including, for example, processor(s), memories, and other circuitry as in UE 10, gNB 70, and backbone network 90. ​​In Figure 1B, gNB 70 is split into two parts, CU 150-1 (on Earth) and DU 150-2 (on a satellite 110), each of which has circuitry as shown in the corresponding dashed boxes. In Figure 1C, gNB 70 is moved to a corresponding satellite 110. In Figure 4, a user equipment (UE) 10 is in wireless communication via radio link 11 with base station 70 of cellular network 1. A UE 10 is a wireless communication device, such as a mobile device, configured to access a cellular network. The UE 10 is illustrated with one or more antennas 28. The ellipses 2 indicate that there could be multiple UE 10s in wireless communication via radio links with base station 70. The UE 10 includes one or more processors 13, one or more memories 15, and other circuitry 16. The other circuitry 16 includes one or more receivers (Rx(s)) 17 and one or more transmitters (Tx(s)) 18. A program 12 is used to make the UE 10 perform the operations described herein. For a UE 10, the other circuitry 16 could include circuitry such as for user interface elements (not shown) such as a display. Base station 70, as a network element of cellular network 1, provides UE 10 with access to cellular network 1 and data network 91 via backbone network 90 (for example, via a user plane function (UPF) of backbone network 90). Base station 70 is illustrated as having one or more antennas 58. In general, base station 70 may be referred to as RAN node 70, although many will refer to it as a gNB (gNode B, a base station for NR, new radio) instead. There are, however, many other examples of RAN nodes, including an eNB (evolved Node B) or TRP (transmit-receive point). The base station 70 includes one or more processors 73, one or more memories 75 and other circuitry 76. The other circuitry 76 includes one or more receivers (Rx(s)) 77 and one or more transmitters (Tx(s)) 78. A program 72 is used to make the base station 70 perform the operations described in this document. It should be noted that base station 70 can be deployed instead using other wireless technologies, such as Wi-Fi (a wireless networking protocol that devices use to communicate without direct wired connections). In the case of Wi-Fi, link 11 could be characterized as a wireless link. Two or more base stations 70 communicate using, for example, link(s) 79. Link(s) 79 may be wired or wireless or both and may implement, for example, an Xn interface for 5G (fifth generation), an X2 interface for LTE (long-term evolution) or another interface suitable for other standards. The cellular network 1 may include a backbone network 90, as a third element or elements illustrated, which may include backbone functionality and provides connectivity via a link or links 81 to a data network 91, such as a telephone network and / or a data communications network (e.g., the Internet). The backbone network 90 includes one or more processors 93, one or more memories 95, and other circuitry 96. The other circuitry 96 includes one or more receivers (Rx(s)) 97 and one or more transmitters (Tx(s)) 98. A program 92 is used to make the backbone network 90 perform the operations described herein. The backbone network 90 could be a 5GC (5G backbone network). The backbone network 90 can implement or comprise multiple network functions (NF) 99, and program 92 can comprise one or more of the NF 99. A 5G backbone network can use hardware such as memory and processors and a virtualization layer. It could be a single standalone computing system, a distributed computing system, or a cloud computing system. The NF 99, as network elements, of the backbone network could be containers or virtual machines running on the hardware of the computing system(s) that make up the backbone network 90. Core network functionality for 5G may include access and mobility management functionality provided by a network function such as an Access and Mobility Management (AMF) function, and session management functionality provided by a network function such as a Session Management Function (SMF). The core network for access and mobility management in an LTE network (long-term evolution) can be provided by an MME (Mobility Management Entity) and / or SGW (Service Gateway) functionality, which routes data to the data network. Many others are possible, as illustrated in the examples in Figure 4: AMF; SMF; MME; SGW; GMLC (Gateway Mobile Location Center); LMF (Location Management Functions); UDM (Unified Data Management) / UDR (Unified Data Repository); NRF (Network Repository Function); and / or E-SMLC (Evolved Service Mobile Location Center). These are merely illustrative core network functionality that may be provided by Core Network 90, and note that core network functionality for both 5G and LTE could be provided by Core Network 90. ​​RAN Node 70 is coupled to Core Network 90 via a backlink 31.The RAN node 70 and core network 90 may include an NG (Next Generation) interface for 5G, or an S1 interface for LTE, or another interface suitable for other radio access technologies to communicate through the backhaul link 31. In the data network 91, there is a computer-readable medium 94. The computer-readable medium 94 contains instructions which, when downloaded and installed in the memories 15, 75, or 95 of the UE 10, the base station 70, and / or the corresponding backbone network element(s) 90, and executed by the processor(s) 13, 73, or 93, cause the respective device to perform corresponding actions described herein. The computer-readable medium 94 may be implemented in other forms, such as via a compact disc or memory card. Programs 12, 72, and 92 contain instructions stored by a or more corresponding 15, 75, or 95 memories. These instructions, when executed by the one or more corresponding 13, 73, or 93 processors, cause the corresponding 10, 70, or 90 apparatus to perform the operations described herein. The computer-readable memories 15, 75, and 95 may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, flash memory, firmware, magnetic memory devices and systems, optical memory devices and systems, fixed memory, and removable memory. The computer-readable memories 15, 75, and 95 may be a means of performing functions of Storage. The processors 13, 73, and 93 can be of any type suitable to the local technical environment and may include one or more general-purpose computers, special-purpose computers, microprocessors, digital signal processors (DSPs), and processors based on multi-core processor architecture, as non-limiting examples. The processors 13, 73, and 93 can be a means of enabling their respective devices to perform functions, such as those described herein. Receivers 17, 77, and 97 and transmitters 18, 78, and 98 can implement wired or wireless interfaces. Receivers and transmitters can be grouped together as transceivers. Cellular network 1 can implement network virtualization, which is the process of combining hardware and software network resources and network functionality into a single software-based management entity—a virtual network. Network virtualization involves platform virtualization, Network virtualization is often combined with resource virtualization. It is categorized either as external, combining many networks, or parts of networks, into a virtual unit, or as internal, providing network-like functionality to software containers on a single system. Note that virtualized entities (such as network functions 99) resulting from network virtualization are still implemented, at some level, using hardware such as processors 73 and / or 93 and memories 75 and / or 95, and such virtualized entities also create technical effects. In general, the various embodiments of user equipment 10 may include, but are not limited to, cellular phones (such as smartphones, mobile phones, cell phones, Voice over Internet Protocol (IP) (VoIP) phones and / or wireless local loop phones), tablets, laptops, vehicles or vehicle-mounted devices for, for example, V2X (vehicle-to-everything) wireless communication, image capture devices such as digital cameras, gaming devices, music storage and playback devices, Internet devices (including Internet of Things, IoT, devices), IoT devices with sensors and / or actuators for, for example, automation applications, as well as handheld units or terminals incorporating combinations of such functions, laptop embedded equipment (LEE), laptop mounted equipment (LME), universal serial bus (USB) keys,smart devices, wireless on-premises equipment (CPE), an Internet of Things (IoT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and applications (e.g., remote surgery), a device and applications of a Industrial (e.g., a robot and / or other wireless devices operating in an industrial and / or automated processing line context), a consumer electronics device, a device operating on commercial and / or industrial wireless networks, and the like. In other words, the UE 10 could be any endpoint device capable of wireless communication. For illustrative purposes, rather than as a limitation, the UE may also be referred to as a communication device, terminal device (MT), subscriber station (SS), portable subscriber station, mobile station (MS), or access terminal (AT). Without limiting in any way the scope, interpretation, or application of the following claims, one technical effect and / or advantage of one or more of the exemplary embodiments disclosed herein is to avoid an L3 handover with the associated signaling and delays. Another technical effect and / or advantage of one or more of the exemplary embodiments disclosed herein is to save RACH (Random Access Channel) resources because the RACH is not being used. The following are additional examples. Example 1. A method comprising: receiving, by a user device connected via a current cell served by a first satellite to a base station, information from the base station comprising information for assisting with a cell switch from the current cell to a cell served by a second satellite, wherein the information is received before a holding time indicating when the current cell will cease serving the user device; and performing, by the user device, the cell switch from the current cell to the cell served by the second satellite using at least the Assistance information for finding one or more cell synchronization blocks for the one served by the second satellite. Example 2. The method according to Example 1, wherein: the assistance information comprises one or more time offsets relative to an existing cell timing for the current cell; and performing the cell switching uses at least the one or more time offsets to find the one or more cell timing blocks for the cell served by the second satellite. Example 3. The method according to either Examples 1 or 2, wherein: the assistance information comprises a frequency offset of one or more cell synchronization blocks to be used for the detection, measurement, and evaluation of the one or more cell synchronization blocks of the cell served by the second satellite; and performing cell switching uses at least the frequency offset to find the one or more cell synchronization blocks for the cell served by the second satellite. Example 4. The method according to Example 3, wherein: the assistance information comprises an additional frequency offset value, wherein a first frequency offset is an offset to a first subcarrier of one or more cell synchronization blocks used by the current cell, and the additional frequency offset value is from the first frequency offset to a first subcarrier of the one or more cell synchronization blocks to be used for synchronization for the cell served by the second satellite; and performing cell switching uses at least the first frequency offset and the additional value to find the one or more blocks of cell synchronization for the synchronization for the cell served by the second satellite. Example 5. The method according to Example 1, wherein: the assistance information comprises a different set of time and frequency locations for the one or more cell synchronization blocks that are provided correspondingly to the cell served by the second satellite, wherein the different set of locations is different from a set of time and frequency locations for one or more cell synchronization blocks corresponding to the current cell; and performing cell switching uses at least the different set of locations to find the one or more cell synchronization blocks for the cell served by the second satellite. Example 6. The method according to any of Examples 1 to 5, wherein: the assistance information comprises a time interval for the user equipment to perform a search for a resynchronization attempt with the cell served by the second satellite; and performing the cell switching uses at least the time interval to find the one or more cell synchronization blocks for the cell served by the second satellite. Example 7. The method in accordance with any of Examples 1 to 6, wherein: the assistance information comprises ephemeris information corresponding to the second satellite to be applied when attempting a resynchronization with the cell served by the second satellite; and performing the cell switching uses at least the ephemeris information to find the one or more cell synchronization blocks for the cell served by the second satellite. Example 8. The method in accordance with any of Examples 1 to 7, wherein cell switching uses either a change in the physical cell identification between the current cell and the cell served by the second satellite, or the same physical cell identification for both the current cell and the cell served by the second satellite. Example 9. The method in accordance with any of Examples 1 to 8, wherein the one or more cell synchronization blocks comprise one or more corresponding synchronization signal blocks comprising both search signals and physical broadcast channels. Example 10. The method in accordance with any of examples 1 to 9, where both the current cell and the cell served by the second satellite cover the same geographical area. Example 11. The method in accordance with any of Examples 1 to 10, wherein cell switching comprises flexible cell switching where there is overlapping satellite coverage at least at one switching time. Example 12. A method comprising: sending, by a base station to a connected user equipment using a current cell served by a first satellite to the base station, information from the base station comprising assistance information for a cell switch from the current cell to a cell served by a second satellite; and turning off, by the base station, the current cell at a downtime. Example 13. The method according to Example 12, further comprising, prior to shutdown, sending one or more cell synchronization blocks to the cell served by a second satellite according to the Cell switching assistance information. Example 14. The method according to Example 12, further comprising, prior to shutdown, communicating with another base station such that the other base station sends one or more cell synchronization blocks in accordance with the cell switching assistance information. Example 15. The method in accordance with any of Examples 12 to 14, wherein: attendance information comprises one or more time offsets relative to an existing cell timing for the current cell. Example 16. The method in accordance with any of Examples 12 to 15, wherein: the assistance information comprises a frequency offset of one or more cell synchronization blocks to be used for the detection, measurement and evaluation of the one or more cell synchronization blocks of the cell served by the second satellite. Example 17. The method according to Example 16, wherein: the assistance information comprises an additional frequency offset value, wherein a first frequency offset is an offset to a first subcarrier of one or more cell synchronization blocks used by the current cell, and the additional frequency offset value is from the first frequency offset to a first subcarrier of the one or more cell synchronization blocks to be used for synchronization for the cell served by the second satellite. Example 18. The method in accordance with any of Examples 12 to 14, wherein: the attendance information comprises a different set of time and frequency locations for the one or more synchronization blocks of cell that is provided correspondingly to the cell served by the second satellite, wherein the different set of locations is different from a set of locations in time and frequency for one or more cell synchronization blocks corresponding to the current cell. Example 19. The method according to any of examples 12 to 18, where: the assistance information comprises a time interval for the user equipment to perform a search for a resynchronization attempt with the cell served by the second satellite. Example 20. The method according to any of examples 12 to 19, where: assistance information comprises ephemeris information corresponding to the second satellite to be applied when attempting a resynchronization with the cell served by the second satellite. Example 21. The method according to any of examples 12 to 20, where cell switching uses either a change in the physical cell identification between the current cell and the cell served by the second satellite, or the same physical cell identification for both the current cell and the cell served by the second satellite. Example 22. The method according to any of examples 12 to 21, wherein the one or more cell synchronization blocks comprise one or more corresponding synchronization signal blocks comprising both search signals and physical broadcast channels. Example 23. The method according to any of examples 12 to 22, where both the current cell and the cell served by the second satellite cover the same geographical area. Example 24. The method according to any of examples 12 to 23, wherein cell switching comprises flexible cell switching where there is overlapping satellite coverage at least at one switching time. Example 25. A computer program, comprising instructions for performing the methods of any of Examples 1 to 11, when the computer program is executed on a device. Example 26. The computer program according to Example 25, wherein the computer program is a computer program product comprising a computer-readable medium carrying instructions incorporated therein for use with the apparatus. Example 27. The computer program according to example 25, wherein the computer program is directly loadable into an internal memory of the device. Example 28. An apparatus comprising means for performing: receiving, by a user equipment connected using a current cell served by a first satellite to a base station, information from the base station comprising assistance information for a cell switch from the current cell to a cell served by a second satellite, wherein the information is received before a holding time indicating when the current cell will cease serving the user equipment; and performing, by the user equipment, the cell switch from the current cell to the cell served by the second satellite using at least the assistance information to find one or more cell synchronization blocks for the cell served by the second satellite. Example 29. The device according to Example 28, wherein: the assistance information comprises one or more time offsets in relationship with an existing cell timing for the current cell; and perform cell switching using at least one or more time offsets to find one or more cell timing blocks for the cell served by the second satellite. Example 30. The apparatus according to either of Examples 28 or 29, wherein: the assistance information comprises a frequency offset of one or more cell synchronization blocks to be used for the detection, measurement and evaluation of the one or more cell synchronization blocks of the cell served by the second satellite; and performing cell switching uses at least the frequency offset to find the one or more cell synchronization blocks for the cell served by the second satellite. Example 31. The apparatus according to Example 30, wherein: the assistance information comprises an additional frequency offset value, wherein a first frequency offset is an offset to a first subcarrier of one or more cell synchronization blocks used by the current cell, and the additional frequency offset value is from the first frequency offset to a first subcarrier of the one or more cell synchronization blocks to be used for synchronization for the cell served by the second satellite; and performing cell switching uses at least the first frequency offset and the additional value to find the one or more cell synchronization blocks for synchronization for the cell served by the second satellite. Example 32. The apparatus according to example 28, wherein: the 44 2848635 44 of 56 assistance information comprises a different set of time and frequency locations for the one or more cell synchronization blocks that are provided correspondingly to the cell served by the second satellite, wherein the different set of locations is different from a set of time and frequency locations for one or more cell synchronization blocks corresponding to the current cell; and performing cell switching uses at least the different set of locations to find the one or more cell synchronization blocks for the cell served by the second satellite. Example 33. The apparatus according to any of Examples 28 to 32, wherein: the assistance information comprises a time interval for the user equipment to perform a search for a resynchronization attempt with the cell served by the second satellite; and performing cell switching uses at least the time interval to find the one or more cell synchronization blocks for the cell served by the second satellite. Example 34. The apparatus according to any of Examples 28 to 33, wherein: the assistance information comprises ephemeris information corresponding to the second satellite to be applied when attempting a resynchronization with the cell served by the second satellite; and performing cell switching uses at least the ephemeris information to find the one or more cell synchronization blocks for the cell served by the second satellite. Example 35. The apparatus in accordance with any of Examples 28 to 34, wherein cell switching uses one of a change in identification of physical cell between the current cell and the cell served by the second satellite, or the same physical cell identification for both the current cell and the cell served by the second satellite. Example 36. The apparatus according to any of Examples 28 to 35, wherein the one or more cell synchronization blocks comprise one or more corresponding synchronization signal blocks comprising both search signals and physical broadcast channels. Example 37. The apparatus in accordance with any of examples 28 to 36, wherein both the current cell and the cell served by the second satellite cover the same geographical area. Example 38. The apparatus according to any of Examples 28 to 37, wherein the cell switching comprises flexible cell switching where there is overlapping satellite coverage at least at one switching time. Example 39. An apparatus comprising means for performing: sending, by a base station to a connected user equipment using a current cell served by a first satellite to the base station, information from the base station comprising assistance information for a cell switch from the current cell to a cell served by a second satellite; and turning off, by the base station, the current cell at a current location at a stop time. Example 40. The apparatus according to Example 39, wherein the means are further configured to: before shutdown, send one or more cell synchronization blocks in the cell served by a second satellite according to the switching assistance information of cell. Example 41. The apparatus according to Example 39, wherein the means are further configured to: before shutdown, communicate with another base station such that the other base station sends one or more cell synchronization blocks in accordance with the cell switching assistance information. Example 42. The apparatus according to any of Examples 39 to 41, wherein: the assistance information comprises one or more time offsets relative to an existing cell timing for the current cell. Example 43. The apparatus according to any of Examples 39 to 42, wherein: the assistance information comprises a frequency offset of one or more cell synchronization blocks to be used for the detection, measurement and evaluation of the one or more cell synchronization blocks of the cell served by the second satellite. Example 44. The apparatus according to Example 43, wherein: the assistance information comprises an additional value of a frequency offset, wherein a first frequency offset is an offset to a first subcarrier of one or more cell synchronization blocks used by the current cell, and the additional frequency offset value is from the first frequency offset to a first subcarrier of the one or more cell synchronization blocks to be used for synchronization for the cell served by the second satellite. Example 45. The apparatus according to any of Examples 39 to 41, wherein: the assistance information comprises a different set of 47 2848635 47 of 56 time and frequency locations for the one or more cell synchronization blocks that are provided correspondingly to the cell served by the second satellite, wherein the different set of locations is different from a set of time and frequency locations for one or more cell synchronization blocks corresponding to the current cell. Example 46. The apparatus according to any of examples 39 to 45, where: the assistance information comprises a time interval for the user equipment to perform a search for a resynchronization attempt with the cell served by the second satellite. Example 47. The apparatus according to any of examples 39 to 46, where: assistance information comprises ephemeris information corresponding to the second satellite to be applied when attempting a resynchronization with the cell served by the second satellite. Example 48. The apparatus according to any of examples 39 to 47, where cell switching uses either a change in the physical cell identification between the current cell and the cell served by the second satellite, or the same physical cell identification for both the current cell and the cell served by the second satellite. Example 49. The apparatus according to any of examples 39 to 48, wherein the one or more cell synchronization blocks comprise one or more corresponding synchronization signal blocks comprising both search signals and physical broadcast channels. Example 50. The apparatus according to any of examples 39 to 49, where both the current cell and the cell served by the second satellite cover the same geographical area. Example 51. The apparatus according to any of Examples 39 to 50, wherein the cell switching comprises flexible cell switching where there is overlapping satellite coverage at least at one switching time. Example 52. The apparatus of any example of apparatus above, wherein the means comprise: at least one processor; and at least one memory that stores instructions which, when executed by at least one processor, cause execution by the apparatus. Example 53. An apparatus comprising: one or more processors; and one or more memories storing instructions which, when executed by the one or more processors, cause the apparatus to at least: receive, by a user equipment connected using a current cell served by a first satellite to a base station, information from the base station comprising assistance information for a cell switch from the current cell to a cell served by a second satellite, wherein the information is received before a holding time indicating when the current cell will cease serving the user equipment; and perform, by the user equipment, the cell switch from the current cell to the cell served by the second satellite using at least the assistance information to find one or more cell synchronization blocks for the cell served by the second satellite. Example 54. An apparatus comprising: one or more processors; and one or more memories that store instructions which, when executed by the one or more processors, cause the apparatus to at least: send, via a base station to a connected user equipment using a current cell served by a first satellite to the base station, information from the station base comprising assistance information for a cell switch from the current cell to a cell served by a second satellite; and turning off, by the base station, the current cell at a current location at a stop time. As used in this application, the term "circuitry" may refer to one or more or all of the following: (a) hardware-only circuit implementations (such as analog-only and / or digital circuitry implementations) and (b) combinations of hardware and software circuits, such as (as applicable): (i) a combination of analog and / or digital hardware circuit(s) with software / firmware and (ii) any portion of hardware processor(s) with software (including digital signal processor(s)), software and memory(s) working together to make a device, such as a mobile phone or server, perform various functions) and (c) hardware circuit(s) and / or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), which require software (e.g., firmware) for operation, but the software may not be present when it is not required for operation. This definition of circuitry applies to all uses of this term in this application, including in any claim. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or a portion of a hardware circuit or processor and its accompanying software and / or firmware. The term circuitry also covers, for example, and if it is applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in a server, cellular network device or other computer or network device. The embodiments in this document can be implemented in software (executed by one or more processors), hardware (for example, an application-specific integrated circuit), or a combination of software and hardware. In an illustrative embodiment, the software (for example, application logic, an instruction set) is maintained on any one of several conventional computer-readable media. In the context of this document, a "computer-readable medium" can be any medium or media capable of containing, storing, communicating, propagating, or transporting instructions for use by or in connection with an instruction-execution system, apparatus, or device, such as a computer, with an example of a computer described and represented, for example, in Figure 4.A computer-readable medium may comprise a computer-readable storage medium (e.g., memories 15, 75, and 95 or other device) which may be any medium or media capable of containing, storing, and / or carrying instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer. A computer-readable storage medium does not comprise propagating signals and may therefore be considered non-transient. The term "non-transient," as used herein, is a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation on the persistence of data storage (e.g., RAM, memory). random access, as opposed to ROM, read-only memory). If desired, the different functions analyzed in this document can be performed in a different order and / or concurrently between sL. In addition, if desired, one or more of the functions described above can be optional or can be combined. Although various aspects of the invention are set forth in the independent claims, other aspects of the invention comprise other combinations of features of the described embodiments and / or the dependent claims with the features of the independent claims, and not only the combinations explicitly set forth in the claims. It is also noted in this document that, although the foregoing describes exemplary embodiments of the invention, these descriptions should not be viewed in a limiting sense. Instead, there are several variations and modifications that can be made without departing from the scope of the present invention as defined in the appended claims. The following abbreviations that may be found in the descriptive report and / or the figures in the drawings are defined as follows: 3GPP third generation partnership project 5G fifth generation 6G sixth generation AMF access and mobility management function ARFCN absolute radio frequency channel number BS base station BW bandwidth CORESET CN set of control resources spinal cord network CSI-RS channel status information reference signal CU central unit 5 DL downlink (from network to UE) DU distributed unit EFC cell fixed to the Earth E-SMLC evolved service mobile location center GMLC mobile gateway location center 10 GW gangway eNB (or eNodeB) evolved node B (for example, a base station of LTE) gNB (or gNodeB) 5G / NR base station ID ID 15 IE information element I / F interface FR1 frequency interval 1 FR2 frequency interval 2 L3 layer 3 20 LMF location management function LS declaration of coordination LTE long-term evolution MME mobility management entity NF network function 25 ng or NG next generation NR NRF new radio network repository function NTN non-terrestrial network N / W or NW grid 5 OFDM orthogonal frequency division multiplexing Option option PBCH physical broadcasting channel PCI Physical cell ID PSS primary synchronization signal 10 PRB physical resources block PUCCH physical uplink control channel RAN radio access network RAN2, RAN3 different TSGs at the helm of 3GPP Rel edition 15 RLF radio link failure Rx receiver SGW service gateway SMF session management function SSB synchronization signal block 20 SS / PBCH synchronization signal / physical broadcast channel SSS secondary synchronization signal sync synchronize TN terrestrial network TRP transmission-reception point 25 TSG group of technical specifications Tx transmitter UDM unified data management UDR unified data repository EU user equipment (for example, a device 5 wireless, usually mobile) UL uplink (from UE to network) UPF user plan function PABLO SCHMUKLER - 20117733352 Digitally signed by PORTALTRAMITES - INPI Date: 2024.08.02 15:11:13 -03:00 Reason: Digitally Signed by the INPI Location: Buenos Aires, Argentina 2848635 56 of 56

Claims

1. A method for using satellite switching assistance information, characterized by: receiving, from a base station through a cell served by a first satellite, information comprising assistance information for a satellite switching from the first satellite to a second satellite for the cell, wherein the information is received before a stop time indicating when the first satellite will cease serving a user equipment through the cell, and wherein the assistance information comprises one or more time offsets relative to a timing of the cell served by the first satellite to find one or more synchronization signal blocks, SSB;and perform satellite switching from the first satellite to the second satellite using at least the assistance information to find one or more SSBs for the cell served by the second satellite, wherein the cell served by the first satellite has the same physical cell identity, PCI, as the cell served by the second satellite. 29 Claims follow;