Random access channel transfer (HO) for non-terrestrial networks (NTN)

Description

RANDOM ACCESS CHANNEL TRANSFER (HO) FOR NON-TERRESTRIAL NETWORKS (NTN) BACKGROUND Field

[001] The present invention relates generally to transfer mechanisms for non-terrestrial networks (NTNs). Related technique

[002] A user equipment (UE) can move between non-terrestrial networks (NTNs), between terrestrial networks (TNs), and / or between an NTN and a TN. The system can assist the UE's movement by facilitating the transfer between NTNs, between TNs, and / or between an NTN and a TN. In each network (e.g., NTN and / or TN), the UE can use timing advance (TA) to control the UE's uplink transmission time in that network. Therefore, the uplink transmissions of all UEs can be synchronized when the uplink transmissions are received by a base station (BS). TA is a special command (e.g., notification) from the BS to the UE to enable the UE to adjust its uplink transmission. For example, the UE can start transmitting an uplink frame (UL) at the TA value before a downlink frame (DL) is received at the UE. SUMMARY

[003] Some aspects of this invention relate to apparatus and methods for implementing mechanisms for random access channel-free (RACH) transfer over non-terrestrial networks (NTN). According to some aspects, a user device (UE) supports RACH-free transfer over NTN and the destination and source cells / nodes support RACH-free transfer. Petition 870250088702, dated 09 / 30 / 2025, page 9 / 81 2 / 49 According to some aspects, and as discussed in more detail below, the network (NW) indicates the non-RACH transfer command to transfer the UE to a destination NTN cell. In the non-RACH HO command, the NW may provide a time advance (TA) setting of the destination NTN cell. In some examples, the TA setting of the destination NTN cell may be provided beforehand. The UE is configured to derive a TA value for the destination NTN cell based on the TA setting in the transfer command. The UE applies the TA value and transmits an initial uplink transmission (UL) (e.g., a full transfer) using a valid first physical uplink shared channel (PUSCH) resource.After the UE receives a medium access control (MAC) response from NW, the UE can initiate data transmission to the destination NTN cell.

[004] Some aspects of this invention relate to a user equipment (UE). The UE includes a transceiver configured to communicate wirelessly with a source base station and a processor communicatively coupled to the transceiver. The processor is configured to receive, using a transceiver and from the source base station, a transfer command to perform a random access channel-free transfer (RACH) operation to a destination base station. The transfer command includes a time advance (TA) setting. The processor is further configured to determine, based on the TA setting of the transfer command, a TA value for uplink transmission (UL) to the destination base station. The processor is further configured to transmit, using the transceiver and to the destination base station, an initial UL transmission based on the TA value. Petition 870250088702, dated 09 / 30 / 2025, page 10 / 81 3 / 49 determined.

[005] In some respects, the TA configuration indicates that a TA value associated with the source base station should be used. To determine the TA value for UL transmission to the destination base station, the processor is configured to determine the TA value associated with the source base station and use the TA value associated with the source base station as the TA value for UL transmission to the destination base station.

[006] In some respects, the TA configuration indicates one or more parameters of a TA value associated with the source base station that should be used. To determine the TA value for UL transmission to the destination base station, the processor is configured to determine one or more parameters of the TA value associated with the source base station and use one or more parameters of the TA value associated with the source base station to compute the TA value for UL transmission to the destination base station.

[007] In some respects, the one or more parameters of the TA value associated with the origin base station that must be used include one or more of a common TA value, a UE-specific TA value, or an initial time alignment value.

[008] In some respects, the TA configuration indicates the transfer without RACH without providing information regarding the TA value for UL transmission to the destination base station. To determine the TA value for UL transmission to the destination base station, the processor is configured to assume that an initial time alignment value has a value of 0 and compute a common TA value, a UE-specific TA value, and a TA offset value. The processor is further configured to use the initial time alignment value, the common TA value, the UE-specific TA value, and the TA offset value to compute the Petition 870250088702, dated 09 / 30 / 2025, page 11 / 81 4 / 49 TA value for UL transmission to the destination base station.

[009] In some respects, the TA setting indicates a type of transfer that is used for non-RACH transfer. To determine the TA value for UL transmission to the destination base station, the processor is configured to compute the TA value for UL transmission to the destination base station based on the type of transfer indicated in the TA setting.

[0010] In some respects, the processor is further configured to receive, using a transceiver and from the destination base station, a reply message confirming the transfer without RACH and to perform the data transmission to the destination base station based on the determined TA value.

[0011] Some aspects of this invention relate to a method implemented by a user equipment (UE) including receiving, from a source base station, a transfer command to perform a random access channel-free transfer (RACH) operation to a destination base station. The transfer command includes a time advance (TA) setting. The method further includes determining, based on the TA setting of the transfer command, a TA value for uplink (UL) transmission to the destination base station and transmitting, using the transceiver and to the destination base station, an initial UL transmission based on the determined TA value.

[0012] Some aspects of this invention relate to a non-transient, computer-readable medium that stores instructions. When the instructions are executed by a processor in a user equipment (UE), the instructions cause the UE to perform operations including receiving, from a source base station, a transfer command to perform a random access channel-free transfer (RACH) operation to a base station of Petition 870250088702, dated 09 / 30 / 2025, page 12 / 81 5 / 49 destination. The transfer command includes a time advance (TA) setting. The operations additionally include determining, based on the TA setting of the transfer command, a TA value for uplink (UL) transmission to the destination base station and transmitting, using the transceiver and to the destination base station, an initial UL transmission based on the determined TA value. The operations additionally include receiving, from the destination base station and in response to the initial UL transmission, a reply message confirming the transfer without RACH and performing the data transmission to the destination base station based on the determined TA value.

[0013] This Summary is provided merely for illustrative purposes of some aspects to provide an understanding of the subject matter described herein. Consequently, the features described above are merely examples and should not be interpreted in such a way as to restrict the scope or spirit of the subject matter of this invention. Other features, aspects and advantages of this invention will become apparent from the detailed description, Figures and claims that follow. BRIEF DESCRIPTION OF THE FIGURES

[0014] The attached drawings, which are incorporated herein and form part of the descriptive report, illustrate the present invention and, together with the description, further serve to explain the principles of the invention and enable one (or more) skilled person(s) in the art to produce and use the invention.

[0015] Figure 1A illustrates an example system implementation mechanism for RACH-free transfer to NTN, according to some aspects.

[0016] Figures 1B to 1E illustrate different example scenarios of RACH-free transfer to NTN, according to some aspects. Petition 870250088702, dated 09 / 30 / 2025, page 13 / 81 6 / 49

[0017] Figure 2 illustrates a block diagram of an example system of an electronic device that implements mechanisms for RACH-free to NTN transfer, according to some aspects.

[0018] Figure 3 illustrates communications between a UE, a source base station and a destination base station to implement RACH-free transfer to NTN, according to some aspects.

[0019] Figure 4 illustrates an example method for a system (e.g., a UE) that implements mechanisms for RACH-free transfer to NTN, according to some aspects.

[0020] Figure 5 illustrates an example method for a system (e.g., a base station) that performs mechanisms for RACH-free transfer to NTN, according to some aspects.

[0021] Figure 6 is an example computer system for implementing some aspects or some portion(s) thereof.

[0022] The present invention is described with reference to the accompanying drawings. In the drawings, generally, similar reference numbers indicate identical or functionally similar elements. Additionally, generally, the digit(s) to the left of a reference number identify the drawing in which the reference number first appears. DETAILED DESCRIPTION

[0023] Some aspects of this invention relate to apparatus and methods for implementing mechanisms for RACH-free transfer to NTN. According to some aspects, and as discussed in more detail below, a network (NW) indicates the RACH-free transfer command to transfer the UE to a destination NTN cell. In the RACH-free HO command, the NW can provide a time advance (TA) setting of the destination NTN cell. In some examples, the TA setting of the destination NTN cell can be Petition 870250088702, dated 09 / 30 / 2025, page 14 / 81 7 / 49 previously provided. The UE is configured to derive a TA value for the destination NTN cell based on the TA configuration in the transfer command. The UE applies the TA value and transmits an initial uplink transmission (UL) (e.g., a full transfer) using a valid first uplink shared physical channel (PUSCH) resource. After the UE receives a Media Access Control (MAC) response element from NW, the UE can initiate data transmission to the destination NTN cell.

[0024] In some instances, aspects of this invention may be implemented by a network and / or a UE operating in accordance with 5th generation wireless technology (5G) for digital cellular networks, as defined by the 3rd generation partnership project (3GPP). Additionally or alternatively, aspects of this invention may be implemented by a network and / or a UE operating in accordance with application 15 (Rel-15), Rel-16, Rel-17, Rel-17 new radio (NR), Rel-17 NTN, Rel-18, Rel-18 NR, Rel-18 NTN or others. However, aspects of this invention are not limited to these instances and one or more mechanisms of this invention may be implemented by other network(s) and / or UE(s) for non-RACH transfer to NTN.

[0025] In some respects, NTNs may refer to networks, or segments of networks, using an aerial or space vehicle for transmission. For example, space vehicles may include one or more low Earth orbit (LEO) satellites, one or more medium Earth orbit (MEO) satellites, one or more geostationary orbit (GEO) satellites, highly elliptical orbit (HEO) satellites, and / or similar. In some examples, aerial vehicles may include high-altitude platforms (HAPS). However, Petition 870250088702, dated 09 / 30 / 2025, p. 15 / 81 8 / 49 The aspects of this invention are not limited to these examples and may include other NTNs.

[0026] In some respects, NTNs can be used for a plurality of scenarios. Some exemplary situations in which NTNs are used may include, but are not limited to, meeting mobile broadband needs, meeting public safety needs in underserved / underserved areas, maritime, air connectivity, rail or similar. However, the aspects of this invention are not limited to these examples and may include other scenarios in which NTNs are used.

[0027] In some respects, NTNs (e.g., NR NTNs with LEO and GEO) may be compatible to support HAPS and Air-to-Ground (ATG) scenarios. The NTN may use frequency division duplex (FDD). However, time division duplex (TDD) may also be applied to relevant scenarios, such as, but not limited to, HAPS, ATG, or similar. In some examples, fixed ground tracking may be applied, and UEs may have global navigation satellite system (GNSS) capabilities. In some examples, transparent payload may be used, and portable devices may be in frequency range 1 (FR1) (e.g., power class 3).Furthermore, very small aperture terminal (VSAT) devices with an external antenna may be at least in frequency range 2 (FR2 frequency range 2) (for example, using radio access network (RAN) specifications 1 to 3). However, the aspects of this invention are not limited to these examples.

[0028] In some respects, an NTN cell (for example, a cell corresponding to NTN) will cover a cell of Petition 870250088702, dated 09 / 30 / 2025, page 16 / 81 9 / 49 wider radio coverage compared to a terrestrial network (TN) cell (e.g., a TN-matched cell). In other words, in NTN, the coverage of a cell or beam is typically much greater than the cell in TN. In a non-limiting example, the coverage of an NTN cell can extend to multiple countries.

[0029] Figure 1A illustrates an example system 100 that implements mechanisms for RACH-free transfer to NTN, according to some aspects. The example system 100 is provided for illustrative purposes only and does not limit the aspects disclosed. System 100 illustrates an example system that can implement RACH-free transfer. Figures 1B to 1E illustrate different exemplary scenarios of RACH-free transfer to NTN.

[0030] The system 100 may include, but is not limited to, a network node (e.g., a base station such as eNBs, gNBs, and the like) 101 and an electronic device (e.g., a UE) 103 and a satellite 104. The electronic device 103 may be configured to operate based on a wide variety of wireless communication techniques. These techniques may include, but are not limited to, techniques based on 3rd generation partnership project (3GPP) standards. For example, the UE 103 may be configured to operate using Rel-15, Rel-16, Rel-17, Rel-17 NR, Rel-17 NTN, Rel-18, Rel-18 NR, Rel-18 NTN, or others. EU 103 may include, but is not limited to, wireless communication devices, smartphones, laptop computers, desktop computers, tablet computers, personal assistants, monitors, televisions, wearable devices, Internet of Things (IoT), vehicle communication devices and the like.

[0031] Network node 101 (referred to here as base station or cell) may include one or more nodes configured to operate based on a wide variety of wireless communication techniques, such as, but Petition 870250088702, dated 09 / 30 / 2025, page 17 / 81 10 / 49, but not limited to, techniques based on 3GPP standards. For example, base station 101 may include one or more nodes configured to operate using Rel-15, Rel-16, Rel-17, Rel-17 NR, Rel-17 NTN, Rel-18, Rel-18 NR, Rel-18 NTN, or others. Satellite 104 may include one or more satellites as part of LEO satellites, MEO satellites, GEO satellites, HEO satellites, HAPS satellites, ATG satellites, or similar. Satellite 104 may be configured to operate based on a wide variety of wireless communication techniques, such as, but not limited to, techniques based on 3GPP standards. For example, satellite 104 may be configured to operate using Rel-15, Rel-16, Rel-17, Rel-17 NR, Rel-17 NTN, Rel-18, Rel-18 NR, Rel-18 NTN, or others.

[0032] In some respects, satellite 104 and base station 101 are part of the NTN. The NTN may include one or more satellites 104 and one or more base stations 101. Base station 101 may be coupled to a core network (e.g., a 5G core network). The NTN may have a coverage area of ​​108. In some respects, UE 103 may be connected to and may communicate with satellite 104 using a carrier 105 (also referred to here as a service link). In some respects, carrier 105 may include a carrier. Additionally or alternatively, carrier 105 may include two or more component carriers (CCs). In other words, UE 103 may implement carrier aggregation (CA). For example, UE 103 may use multiple carriers for communication with satellite 104.According to some aspects, satellite 104 can be connected to and can communicate with base station 101 using a carrier 107 (also called here a feeder link). According to some aspects, carrier 107 may include one carrier. Additionally or alternatively, carrier 107 may include two. Petition 870250088702, dated 09 / 30 / 2025, page 18 / 81 11 / 49 or more component carriers (CC). In other words, UE 103 can implement carrier aggregation (CA). For example, UE 103 can use multiple carriers for communication with base station 101 via satellite 104.

[0033] In some respects, the UE 103 can move between different networks. For example, the UE 103 can move from a first NTN cell (e.g., a cell associated with the first NTN) to a second NTN cell (e.g., a cell associated with the second NTN different from the first NTN). In another example, the UE 103 can move from an NTN cell to a TN cell (e.g., a cell associated with TN). In yet another example, the UE 103 can move from a TN cell to an NTN cell. System 100 can be configured to facilitate RACH-free transfer for the UE 103. Figures 1B to 1E are discussed below for exemplary RACH-free transfer of the UE 103 between a first NTN cell and a second NTN cell. However, aspects of this invention are not limited to these examples and are applied to other RACH-free transfers.

[0034] In some respects, the UE 103 is not required to connect to an NTN and TN cell simultaneously during transfers. In some instances, the dual active protocol stack (DAPS) is incompatible. In some respects, additional conditions for conditional handover (CHO) are introduced for NTN-specific CHO due to NTN radio characteristics. For example, for NTN-specific characteristics, the variation in signal strength / quality between the cell center and the cell edge is not very pronounced. For NTN-specific CHO conditions, condEventTI and condEventDI can always be configured in conjunction with one of the measurement-based trigger conditions (e.g., CHO events). Petition 870250088702, dated 09 / 30 / 2025, p. 19 / 81 12 / 49 A3 / A4 / A5).

[0035] According to some aspects, for CHO recovery and for the candidate cell with condEventTI, CHO recovery cannot be performed if a T2 timer has not expired. For the candidate cell with condEventDI, CHO recovery can be excluded without checking condEventDI. In some examples, condEventDI can be configured as the normal measurement event for the measurement report. In some aspects, condEventTI and condEventDI are discussed, for example, in the 3rd Generation Partnership Project (3GPP) Technical Specification ETSI TS 138 331 V17.0.0 (05 2022).

[0036] In some examples, the NTN CHO condition may include condEventA4 which can be used for the A4 measurement event (e.g., a neighbor becomes better than a boundary). In some examples, the NTN CHO condition may include condEventTI which can be a time-based trigger condition, and CHO can only run between T1 and T2. In these examples, the network can set T1 (e.g., the boundary t1) and duration using coordinated universal time (UTC). In some examples, the NTN CHO condition may include condEventD1 which can be a location-based trigger condition.A CHO can be executed when the following two conditions are met - (1) a distance between the UE (e.g., UE 103) and a first reference location (e.g., referenceLocation1) is greater than a distance threshold from a first reference (e.g., distanceThreshFromReference1) (distant from a primary serving cell (PCell)) and (2) a distance between the UE (e.g., UE 103) and a second reference location (e.g., referenceLocation2) is less than a distance threshold from a second reference (e.g., distan). Petition 870250088702, dated 09 / 30 / 2025, p. 20 / 81 13 / 49 ce ThreshFromReference2).

[0037] In some respects, RACH-free transfer includes a transfer procedure that does not use (and / or ignores) the RACH procedure. NTN RACH-free transfer can support dynamic allocation of the destination cell for uplink shared physical channel transmission (PUSCH) without RACH to reduce random access congestion in the destination cell. In some instances, RACH-free transfer can be a Layer 3 (L3) mobility procedure and can use the Long Term Evolution (LTE) RACH-free transfer procedure as a baseline. In the LTE RACH-free transfer procedure, the network provides the absolute TA value for access in the destination cell, and the UE can apply the indicated value directly. However, for NTN, only part of the TA value is known by the network side, and the other part is calculated by the UE itself.Therefore, the TA value provided by the LTE non-RACH transfer procedure has deficiencies compared to the NTN non-RACH transfer procedure.

[0038] Consequently, as discussed in more detail below, some aspects of this invention are directed to RACH-free transfer to NTN, where the UE can receive a TA configuration and the UE can use the TA configuration to determine (e.g., compute and / or derive) the TA value. As discussed in more detail below, the UE can use different values ​​in the TA configuration to determine (e.g., compute and / or derive) the TA value based on different RACH-free transfer scenarios.

[0039] According to some aspects, when UE 103 moves from a first NTN cell to a second NTN cell (different from the first NTN cell), UE 103 is configured to... Petition 870250088702, dated 09 / 30 / 2025, page 21 / 81 14 / 49 terminate (e.g., compute and / or derive) a time advance (TA) value for the second NTN cell. UE 103 can use the TA value to control the uplink transmission time of UE 103 in the second NTN cell. Therefore, uplink transmissions from all UEs can be synchronized when uplink transmissions are received, for example, by a base station (BS). As discussed in more detail below, UE 103 can receive a TA setting and UE 103 can use the TA setting to determine (e.g., compute and / or derive) the TA value.

[0040] Although some examples are discussed in the present invention as a transfer between NTN cells, aspects of this invention are not limited to these examples and may include other transfers (for example, between an NTN cell and a TN cell).

[0041] Figures 1B to 1E provide some exemplary RACH-free transfers of UE 103 between a first NTN cell and a second NTN cell, according to some aspects.

[0042] Figure 1B illustrates system 110 with an exemplary RACH-free transfer from UE 103 to an intrasatellite transfer with the same feeder link (e.g., the same base station 101). In this example, UE 103 is connected to and communicates with satellite 104 using carrier 105. Satellite 104 is connected to and communicates with base station 101 using carrier 107. In a non-limiting example, the RACH-free transfer to UE 103 may include UE 103 using the same carrier 105 (also referred to in the present invention as a service link) to connect to and communicate with satellite 104. In this exemplary RACH-free transfer, satellite 104, base station 101, carrier 105, and carrier 107 (also referred to in the present invention as a service link) are all connected to and communicate with satellite 104. Petition 870250088702, dated 09 / 30 / 2025, page 22 / 81 15 / 49 feeder link) remain the same (e.g., intra-satellite transfer with the same feeder link). In some respects, the 108 coverage area may change after the transfer without RACH. Alternatively, after the transfer without RACH, the 108 coverage area may remain the same as before the transfer without RACH.

[0043] As discussed in more detail below, during the non-RACH transfer of Figure 1B, UE 103 can receive a TA configuration from base station 101 via satellite 104. UE 103 can use the TA configuration to determine (e.g., compute and / or derive) the TA value to communicate with base station 101 via satellite 104 using carriers 105 and 107.

[0044] In contrast to the use of the same service link, some aspects of intra-satellite transfer with the same feeder link may include scenarios where the service link is changed (e.g., from 105 to 115). In a non-limiting example, the RACH-free transfer to UE 103 may involve UE 103 using a new carrier 115 (also referred to in the present invention as a service link) to connect and communicate with satellite 104. In this exemplary RACH-free transfer, satellite 104, base station 101, and carrier 107 (also referred to in the present invention as a feeder link) remain the same (e.g., intra-satellite transfer with the same feeder link). However, the carrier (on the service link) is changed from carrier 105 to carrier 115. The change in the carrier may be a change in the component carriers, a change in a frequency of the service link, or similar.Depending on the aspect, the coverage area 108 may change after the transfer without RACH. Alternatively, after the transfer without RACH, the coverage area 108 may remain the same as before. Petition 870250088702, dated 09 / 30 / 2025, page 23 / 81 16 / 49 of the transfer without RACH.

[0045] As discussed in more detail below, during the non-RACH transfer of Figure 1B, UE 103 can receive a TA configuration from base station 101 via satellite 104. UE 103 can use the TA configuration to determine (e.g., compute and / or derive) the TA value to communicate with base station 101 via satellite 104 through carriers 115 and 107.

[0046] Figure 1C illustrates system 120 with an exemplary RACH-free transfer from UE 103 to an intra-satellite transfer with different feeder links (e.g., different base stations). In this example, UE 103 is connected to and communicates with satellite 104 using carrier 105. Satellite 104 is connected to and communicates with base station 101 using carrier 107. In a non-limiting example, the RACH-free transfer to UE 103 may include UE 103 being connected to and communicating with a new base station 121. In this exemplary RACH-free transfer, satellite 104 remains the same, but the base station is changed from base station 101 to base station 121 (e.g., intra-satellite transfer with different feeder links). After the transfer, UE 103 is still connected and communicating with satellite 104 using carrier 105. Now, satellite 104 is connected and communicating with base station 121 using carrier 127.Depending on the aspect, the 108 coverage area may change after the transfer without RACH. Alternatively, after the transfer without RACH, the 108 coverage area may remain the same as before the transfer without RACH.

[0047] As discussed in more detail below, during the non-RACH transfer of Figure 1C, UE 103 can receive a TA configuration from base station 101 via satellite 104. UE 103 can use the TA configuration to determine (e.g., compute) Petition 870250088702, dated 09 / 30 / 2025, page 24 / 81 17 / 49 tar and / or derive) the value of TA to communicate with base station 121 via satellite 104 using carriers 105 and 127.

[0048] Figure 1D illustrates system 130 with an exemplary non-RACH transfer from UE 103 to a transfer between satellites with different feeder links (e.g., different base stations). In this example, UE 103 is connected to and communicates with satellite 104 using carrier 105. Satellite 104 is connected to and communicates with base station 101 using carrier 107. In a non-limiting example, the non-RACH transfer for UE 103 may include UE 103 being connected to and communicating with a new base station 131 via a new satellite 134. In this exemplary non-RACH transfer, satellite 104 is changed to satellite 134 and the base station is changed from base station 101 to base station 131 (e.g., transfer between satellites with different feeder links). After the transfer, UE 103 is now connected and communicating with satellite 134 using carrier 135.Satellite 134 is connected to and communicates with base station 131 using carrier 137. According to some aspects, coverage area 108 may change after the transfer without RACH to coverage area 138. Additionally or alternatively, after the transfer without RACH, coverage area 108 may remain the same as before the transfer without RACH.

[0049] As discussed in more detail below, during the non-RACH transfer of Figure 1D, UE 103 can receive a TA configuration from base station 101 via satellite 104. UE 103 can use the TA configuration to determine (e.g., compute and / or derive) the TA value to communicate with base station 131 via satellite 134 through carriers 135 and 137.

[0050] Figure 1E illustrates system 140 with a RACH-free transfer exemplifying UE 103 for a transfer between Petition 870250088702, dated 09 / 30 / 2025, page 25 / 81 18 / 49 satellites with the same feeder link (e.g., the same base station 101). In this example, UE 103 is connected to and communicates with satellite 104 using carrier 105. Satellite 104 is connected to and communicates with base station 101 using carrier 107. In a non-limiting example, the non-RACH transfer to UE 103 might include UE 103 being connected to and communicating with the same base station 101 via a new satellite 144. In this exemplary non-RACH transfer, satellite 104 is changed to satellite 144, but base station 101 remains the same (e.g., transfer between satellites with the same feeder link). After the transfer, UE 103 is now connected and communicating with satellite 144 using carrier 145. Satellite 144 is connected and communicating with base station 101 using carrier 147. According to some aspects, coverage area 108 may change after the transfer without RACH to coverage area 148.Alternatively, after the transfer without RACH, the coverage area 108 may remain the same as before the transfer without RACH.

[0051] As discussed in more detail below, during the non-RACH transfer of Figure 1E, UE 103 can receive a TA configuration from base station 101 via satellite 104. UE 103 can use the TA configuration to determine (e.g., compute and / or derive) the TA value to communicate with base station 101 via satellite 144 through carriers 105 and 147.

[0052] Figure 2 illustrates a block diagram of an exemplary system 200 of an electronic device implementing mechanisms for RACH-free transfer to NTN, according to some aspects of the invention. System 200 can be any of the electronic devices (e.g., base stations 101, 121, 131, UE 103, satellites 104, 134, 144) of system 100, 110, 120, 130 Petition 870250088702, dated 09 / 30 / 2025, page 26 / 81 19 / 49 and / or 140. System 200 includes a processor 210, one or more transceivers 220, a communication infrastructure 240, a memory 250, an operating system 252, an application 254, and / or one or more antennas 260. The illustrated systems are provided as exemplary parts of system 200, and system 200 may include other circuit(s) and subsystem(s). Furthermore, although the systems of system 200 are illustrated as separate components, aspects of this invention may include any combination of these, with fewer or more components. Additionally, the system 200 of the aspects of this invention may include any number of processors, transceivers, communication infrastructures, memories, operating systems, applications, and antennas.

[0053] Memory 250 may include random access memory (RAM) and / or a cache, and may include control logic (e.g., computer software) and / or data. Memory 250 may include other storage or memory devices, such as, but not limited to, a hard disk drive and / or a removable storage device / unit. In some examples, the operating system 252 may be stored in memory 250. The operating system 252 may manage data transfer between memory 250, one or more applications 254, the processor 210, and / or one or more transceivers 220. In some examples, the operating system 252 maintains one or more network protocol stacks (e.g., an Internet protocol stack, a cellular protocol stack, and the like) that may include several logical layers.In corresponding layers of the protocol stack, the 252 operating system includes the control mechanism and data structures to perform the functions associated with that layer.

[0054] According to some examples, the 254 application can be Petition 870250088702, dated 09 / 30 / 2025, page 27 / 81 20 / 49 stored in memory 250. Application 254 may include applications (e.g., user applications) used by wireless system 200 and / or by a user of wireless system 200. Applications in application 254 may include applications such as, but not limited to, radio transmission, video transmission, remote control, and / or other user applications.

[0055] System 200 may also include communication infrastructure 240. Communication infrastructure 240 provides communication between, for example, processor 210, one or more transceivers 220, and a memory 250. In some implementations, communication infrastructure 240 may be a bus. Processor 210, together with instructions stored in memory 250, performs operations that enable system 200 of systems 100 to 140 to implement mechanisms for RACH-free transfer to NTN, as described herein.

[0056] One or more 220 transceivers transmit and receive communication signals that support the operations of the 200 system, including, but not limited to, mechanisms for non-RACH transceivers for NTN, according to some aspects, and may be coupled to one or more 260 antennas. The one or more 260 antennas may include one or more antennas that may be of the same or different types. The one or more 260 antennas may include one or more MIMO antennas with one or more antenna ports. According to some aspects, each antenna port of the one or more 260 antennas may carry its feature grid and one or more reference signals. The antenna ports of the one or more 260 antennas may be indicated using port numbers. Different antenna ports may be assigned to different channels and / or signals.

[0057] One or more 220 transceivers allow the 200 system to communicate with other devices that may be wired and / or Petition 870250088702, dated 09 / 30 / 2025, page 28 / 81 21 / 49 wireless. In some examples, the one or more 220 transceivers may include processors, controllers, radios, sockets, plugs, buffers, and similar circuits / devices used for connection and communication in networks. According to some examples, the one or more 220 transceivers include one or more circuits for connection and communication with wired and / or wireless networks.

[0058] In some aspects, the one or more 220 transceivers may include a cellular subsystem, a WLAN subsystem, and / or a Bluetooth™ subsystem, each including its own transceiver and radio protocol(s), as will be understood by those skilled in the art based on the discussion provided in the present invention. In some implementations, the one or more 220 transceivers may include more or fewer systems for communication with other devices.

[0059] In some examples, one or more 220 transceivers may include one or more circuits (including a WLAN transceiver) to enable connection(s) and communication over WLAN networks such as, but not limited to, networks based on the standards described in IEEE 802.11. Additionally or alternatively, one or more 220 transceivers may include one or more circuits (including a Bluetooth™ transceiver) to enable connection(s) and communication based on, for example, the Bluetooth™ protocol, the Bluetooth™ Low Energy protocol, or the Bluetooth™ Long Range Low Energy protocol. For example, the 220n transceiver may include a Bluetooth™ transceiver.

[0060] Additionally, one or more 220 transceivers may include one or more circuits (including a cellular transceiver) for connection and communication in cellular networks. Cellular networks may include, but are not limited to, third-generation (3G), fourth-generation (4G), and fifth-generation (5G) networks. Petition 870250088702, dated 09 / 30 / 2025, page 29 / 81 22 / 49 as a universal mobile telecommunications system (UMTS), long-term evolution (LTE) and the like. For example, one or more 220a to 220n transceivers can be configured to operate according to one or more of the Rel-15, Rel-16, Rel-17, Rel-17 NR, Rel-17 NTN, Rel-18, Rel-18 NR, Rel-18 NTN or other 3GPP standards.

[0061] In some respects, the processor 210, alone or in combination with computer instructions stored in memory 250, and / or one or more transceivers 220, implement mechanisms for RACH-free transfer to NTN, as discussed in the present invention.

[0062] Figure 3 illustrates the 300 communications between a UE, a source base station, and a destination base station to implement RACH-free transfer to NTN, according to some aspects. As a convenience and not a limitation, Figure 3 can be described in relation to the elements of Figures 1A to 1E and 2. It should be considered that not all operations in Figure 3 may be necessary, and the operations may not be performed in the same order as shown in Figure 3.

[0063] In some respects, UE 301 is connected and communicates with the source base station 303. UE 301 may be UE 103 of Figures 1A to 1E. The source base station 303 may be base station 101 in Figures 1A to 1E. The source base station 303 may be associated with a source cell in which UE 301 is operating. The source cell may be an NTN cell or a TN cell. As UE 301 moves to a destination cell associated with destination base station 305, the RACH-free transfer procedure is performed so that UE 301 is transferred from source base station 303 to destination base station 305. The destination cell may be an NTN cell or a Petition 870250088702, dated 09 / 30 / 2025, p. 30 / 81 23 / 49 TN cell. In some respects, the destination cell is an NTN cell and the source cell is also an NTN cell. In some respects, the destination cell is an NTN cell and the source cell is also a TN cell. In some respects, UE 301 supports non-RACH transfer in NTN and both the source base station 303 and the destination base station 305 support non-RACH transfer.

[0064] In some respects, source base station 303 and destination base station 305 may perform a transfer preparation without RACH 307. In some instances, during the transfer preparation without RACH 307, source base station 303 may receive measurement(s) from UE 301 and, depending on the measurement(s) received and network conditions, source base station 303 may send a transfer request to destination base station 305. Destination base station 305 may accept or reject the transfer request. Destination base station 305 may send a transfer request response to source base station 305. The transfer preparation without RACH 307 may include other (and / or different) operations between source base station 303 and destination base station 305.

[0065] According to some aspects, then, the originating base station 303 can send the NTN 309 configuration of the destination base station 305 to the UE 301. In some examples, the NTN 309 configuration may include a system information block type 19 (SIB19). The SIB19 may include, but is not limited to, frequency between radio access technologies (RATs) and priority information to be used in the destination cell associated with the destination base station 305. However, the aspects of this invention are not limited to this example and the NTN 309 configuration of the destination base station 305. Petition 870250088702, dated 09 / 30 / 2025, p. 31 / 81 24 / 49 may include other information.

[0066] In some respects, the originating base station 303 can then send transfer command 311 to UE 301. Transfer command 311 may include a non-RACH transfer command that the originating base station 303 can use to instruct UE 301 to transfer to the destination base station 305. In some respects, transfer command 311 may include uplink resource (UL) information for UE 301 to connect and communicate with the destination base station 305. Additionally or alternatively, transfer command 311 may include UL grant to the destination base station 305. Additionally or alternatively, transfer command 311 may include TA configuration associated with the destination base station 305. However, aspects of this invention are not limited to this example, and transfer command 311 may include other (and / or different) information.

[0067] Although Figure 3 illustrates that the TA configuration associated with destination base station 305 is provided using transfer command 311, other methods can be used to provide the TA configuration associated with destination base station 305 to UE 301. For example, the TA configuration associated with destination base station 305 can be provided to UE 301 beforehand (e.g., during transfer preparation without RACH 307 or before transfer preparation without RACH 307).

[0068] After receiving transfer command 311, UE 301 determines (e.g., computes and / or derives) in 313 the TA value associated with destination base station 305 based on the information in transfer command 311. For example, UE 301 determines (e.g., computes and / or derives) the TA value associated with destination base station 305 based on the TA configuration associated with the destination base station. Petition 870250088702, dated 09 / 30 / 2025, page 32 / 81 25 / 49 Destination base station 305 provided in transfer command 311. UE 301 can use the TA value determined for UL transmission from UE 301 to destination base station 305.

[0069] In some respects, communication 300 may include an optional dynamic UL grant 315. For example, destination base station 305 may transmit dynamic UL grant 315 to UE 301. The dynamic UL grant 315 may include a UL grant for the first UL transmission from UE 301 to the destination cell associated with destination base station 305. The dynamic UL grant 315 may include a dynamic schedule for the UL grant. In addition to or alternatively to the optional dynamic UL grant 315, the UL grant for the first UL transmission from UE 301 to the destination cell may be provided in transfer command 311 (e.g., a pre-allocated configured radio resource control (RRC) grant).

[0070] In some respects, UE 301 may transmit the initial UL transmission 317. UE 301 may use the determined TA value (e.g., computed and / or derived) in operation 313 for the initial UL transmission 317. UE 301 may use the granted UL resource (based on the dynamic UL grant 315 and / or transfer command 311) for the initial UL transmission 317. UE 301 may perform the initial UL transmission 317 during the first valid PUSCH resource. In some instances, the initial UL transmission 317 may include a complete transfer message. For example, UE 301 sends the initial UL transmission 317 (e.g., the complete delivery message) to destination base station 305 to indicate to destination base station 305 that UE 301 is now connected and communicating with destination base station 305. Petition 870250088702, dated 09 / 30 / 2025, page 33 / 81 26 / 49

[0071] As indicated in Figure 3, communication 300 does not include a RACH procedure between the transfer command 311 and the initial UL transmission 317. The transfer procedure in Figure 3 is a transfer procedure without RACH.

[0072] In some respects, and in response to the initial UL transmission 317, destination base station 305 may transmit response message 319 to UE 301. In some respects, response message 319 may be an acknowledgment response message confirming receipt of the initial UL transmission 317. In some respects, response message 319 may be any response message. For example, acknowledgment message 319 may include a media access control (MAC) control element (CE). In some examples, the MAC CE may include a contention resolution (CR) MAC CE. In some examples, the MAC CE may include a tracking area code (TAC) MAC CE. In some examples, the MAC CE may include a UE-dedicated MAC CE.

[0073] According to some aspects, after receiving the reply message 319, UE 301 can start data transmission 321 with the destination base station 305 (for example, in the destination cell).

[0074] As discussed above, UE 301 determines (i.e., computes and / or derives) in 313 the TA value associated with the destination base station 305 based at least on the TA configuration associated with the destination base station 305 provided in the transfer command 311. UE 301 can use the TA value for the initial UL transmission 317 and / or for the data transmission 321. For example, a UL frame for transmission from UE 301 starts the TA value before the start of the corresponding downlink frame in UE Petition 870250088702, dated 09 / 30 / 2025, p. 34 / 81 27 / 49 301. According to some aspects, the value of TA can be computed as: TTA=i^TA + WrAíteJfocamentü +NTA?adT +NTA.adj)Tc Equation (1)

[0075] Here, TTA is the value of TA that is determined (e.g., computed and / or derived) by UE 301. Tc is a sampling time and may depend on the spacing between subcarriers. In some examples, Tc = 0.509 ns, however, other values ​​for Tc may be used.

[0076] An initial time alignment value (jvrj) and a TA offset value (NTA.dssiacamsnia) can be provided by and / or computed, for example, from clause 4.2 of ETSI TS 138 213 V15.3.0 (10 2018) (Physical layer procedures for control (3GPP TS 38.213 version 15.3.0 application 15)).

[0077] A common TA value ( / V^^1) can be provided and / or computed, for example, from clause 4.2 of ETSI TS 138 213 V15.3.0 (10 2018) and can be derived from the higher-layer parameters TACommon, TACommonDrift and TACommonDriftVariation, if configured. Otherwise, = °·

[0078] In some instances, UE 301 may determine the common TA value (Λ^™™) based on a one-way propagation delay, as provided, for example, in clause 4.2 of ETSI TS 136 213 V17.2.0 (08 2022) (LTE; Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layer procedures (3GPP TS 36.213 version 17.2.0 application 17)). UE 301 may determine the common TA value (Λ^™”7) based on the NTN configuration of a service satellite (e.g., based on a feeder link delay). Petition 870250088702, dated 09 / 30 / 2025, page 35 / 81 28 / 49 For example, the one-way propagation delay (?ltresoCDnilimO)) can be determined as follows: / Itraso ít) = Ή-----------* (t - tépüCJ +---------------* Equation (2)

[0079] Here, râCDm„m, respectively provided ® ^4^,),,),),,7)^3^)4,-,7,,,-,7,,^3 are responsible for ta-Common, ta-CommonDríft and taCommonDriftVariant and the epoch time of TâCDmi(m, TAc <mn„Mae TAc„mumB„„Vo„-o„„ como discutido em, por exemplo, TS 38.331. The one-way propagation delay (jltraso^^Ct)) can provide a time distance t between a service satellite and an uplink time synchronization reference point divided by the time velocity. The uplink reference point can be a point where the downlink (DL) and the UL are aligned with an offset given by the offset value of TA.

[0080] In some respects, the NTN configuration used for the TA value calculation may be provided in the NTN configuration. In some respects, for the service cell, the NTN configuration is provided in a configuration dedicated to RRC and / or 0 SIB19. In some respects, for a neighboring cell, the NTN configuration may be provided in SIB19. In some respects, the network may use TAC MAC CE to adjust the initial time alignment value (nta value), which may be common as TN and NTN cell.

[0081] A specific EU TA value ( / V^ad7) may be provided and / or computed, for example, by clause 4.2 of ETSI TS 138 Petition 870250088702, dated 09 / 30 / 2025, page 36 / 81 29 / 49 213 V15.3.0 (10 2018) and is calculated by UE 301 based on the UE 301 position and higher layer parameters related to service satellite ephemeris, if configured. Otherwise, N^act; = 0. UE can calculate the specific UE TA value «a,? based on the UE position and service satellite ephemeris information (e.g., using service link delay).

[0082] According to some aspects, the TA (rTJ) value is a combination of service link round-trip time (RTT) and a common TA. The service link RTT is the RTT on the service link between the UE (e.g., UE 301) and the satellite with which the UE communicates. For example, the service link RTT is the RTT on the service link between UE 103 and satellite 104 in Figure 1A. The common TA is a configured offset that corresponds to the RTT between a reference point (RP) and an NTN payload. The RP may be located between the satellite (e.g., satellite 104 in Figure 1A) and a base station (e.g., base station 101 in Figure 1A). The common TA may be part of a feeder link RTT. The feeder link RTT is the RTT on the link feeder line between the satellite (e.g., satellite 104 in Figure 1A) and the base station (e.g., base station 101 in Figure 1A).

[0083] According to some aspects, UE 301 determines (e.g., computes and / or derives) in 313 the TA value associated with the destination base station 305 based at least on the TA configuration associated with the destination base station 305 provided in the transfer command 311 using different options.

[0084] Option 1 - Depending on some aspects, the originating base station 305 can indicate to UE 301 (for example, using the TA configuration in the transfer command 311) to use the va Petition 870250088702, dated 09 / 30 / 2025, page 37 / 81 30 / 49 TA value of the primary service cell (PCell) of origin for UL transmissions to destination base station 305. The originating PCell is and / or is associated with originating base station 305. For example, the TA setting in transfer command 311 may include the TA value (Tta) of destination base station 305 which reuses the TA value of the originating PCell. Additionally or alternatively, the TA setting in transfer command 311 may include information (e.g., one or more parameters) to instruct UE 301 to use the TA value of the originating PCell for UL transmissions to destination base station 305.

[0085] In this case, UE 301 uses the current TA value in the source cell for transmissions in the destination cell (e.g., to destination base station 305) directly. In other words, determining (e.g., computing and / or deriving) the TA value may include determining that the TA setting in transfer command 311 includes the TA value of the source PCell and may further include using the TA value of the source PCell for transmissions in the destination cell. Additionally or alternatively, determining (e.g., computing and / or deriving) the TA value may include determining the information (e.g., one or more parameters) in the TA setting in transfer command 311 that indicates using the TA value of the source PCell.In this illustrative aspect, determining (e.g., computing and / or deriving) the TA value may also include using the current TA value (the TA value of the source PCell that UE 301 is using for the source cell) for transmissions in the destination cell.

[0086] Option 2 - Depending on some aspects, the source base station 305 can indicate to UE 301 (for example, using the TA configuration in the transfer command 311) which TA value parameters to reuse from the source cell and which TA value parameters to compute. For example, the TA configuration Petition 870250088702, dated 09 / 30 / 2025, page 38 / 81 31 / 49 in transfer command 311 can indicate to UE 301 whether the common TA value, the UE-specific TA value ( / v^Ead>), and the initial time alignment value ( / vT4) are the same as the corresponding values ​​used for the TA of the originating PCell. The originating PCell is and / or is associated with originating base station 305. The TA setting in transfer command 311 can indicate to UE 301 regarding one or more of the common TA value, the UE-specific TA value, or the initial time alignment value ( / VT4), separately.

[0087] In some examples, the TA configuration can indicate whether the common TA value, the UE-specific TA value (A^ad>), and / or the initial time alignment value (¾) are the same as the corresponding values ​​used for the source PCell TA using the same corresponding values ​​used for the source PCell TA. Additionally or alternatively, the TA configuration can indicate whether the common TA value, the UE-specific TA value (Ar£fadJ), and / or the initial time alignment value (λττ4) are the same as the corresponding values ​​used for the source PCell TA using parameters in the TA configuration to indicate whether the same information is used or not. For example, the TA configuration can indicate whether the common TA value, the UE-specific TA value ( / v£facW), and / or the initial time alignment value are the same as the corresponding values ​​used for the source PCell TA by the absence or presence of such a parameter. Petition 870250088702, dated 09 / 30 / 2025, page 39 / 81 32 / 49

[0088] In some examples, for the initial time alignment value (JVrJ, the TA setting may also indicate whether the initial time alignment value ( / vT4) is 0.

[0089] Depending on the information in the TA configuration of transfer command 311, UE 301 can use Equation (1) to determine (e.g., compute and / or derive) the TA value for UL transmissions to destination base station 305.

[0090] In one example, the common TA value ( / v^™“™), the UE-specific TA value ( / v^ad7), and the initial time alignment value ( / VT4) are the same as the corresponding values / parameters used for the TA of the originating PCell. UE 301 can use this information (e.g., the corresponding values / parameters used for the TA of the originating PCell) and Equation (1) to determine (e.g., compute and / or derive) the TA value for UL transmissions to the destination base station 305. In some examples, UE 301 can also compute / derive the TA offset value (NTA.dSiÍacamsnJ) for use in Equation (1). This example can be used for intra-satellite transfer with the same feeder link, in some respects.

[0091] In another example, the UE-specific TA value (V^ad7) and the initial time alignment value (ΛTΓ^) are the same as the corresponding values / parameters used for the source PCell TA. UE 301 can use this information (e.g., the corresponding values / parameters used for the source PCell TA), compute / derive the common TA value (A^™”™), and use Equation (1) to determine (e.g., compute and / or derive) the value Petition 870250088702, dated 09 / 30 / 2025, page 40 / 81 33 / 49 of TA for UL transmissions to destination base station 305. In some examples, UE 301 can also compute / derive the offset value of TA for use in Equation (1). This example can be used for intra-satellite transfer with different feeder links (e.g., applicable in GSO), according to some aspects.

[0092] In another example, the common TA value ® is the same as the corresponding value / parameter used for the TA of the originating PCell. UE 301 can use this information (e.g., the corresponding value / parameter used for the TA of the originating PCell), compute / derive the UE-specific TA value ( / v?Jad>) and the initial time alignment value (jvrj, and use Equation (1) to determine (e.g., compute and / or derive) the TA value for UL transmissions to the destination base station 305. In some examples, UE 301 can also compute / derive the TA offset value (NTA.dgs[acamgnta)) for use in Equation (1). This example can be used for same-feeder link transfer, in some respects.

[0093] According to some examples, the specific UE TA value (^adJ) and the initial time alignment value ( / vT4) are either both equal to the corresponding value / parameter used for the source PCell TA or both are different from the corresponding value / parameter used for the source PCell TA.

[0094] According to some aspects, if the feeder links are the same in the transfer, the common TA value remains the same and does not change. Furthermore, if the service links are the same in the transfer (for example, transfer Petition 870250088702, dated 09 / 30 / 2025, page 41 / 81 34 / 49 intra-satellite), the specific TA value of UE ( / v^Ead>) remains the same and does not change.

[0095] Option 3 - Due to some aspects, the originating base station 305 does not provide any information regarding the TA value parameters for UE 301. For example, the TA setting in transfer command 311 does not include any information regarding TA value parameters. The TA setting (and / or transfer command 311) may include information indicating transfer operation without RACH, but does not include information regarding TA value parameters.

[0096] In this example, UE 301 assumes that the initial time alignment value (ATTJ) has a value of 0 (JV^ = 0). UE 301 computes / derives the common TA value ( / v£™“7), the UE Specific TA value (Ar£fadJ) and / or the TA offset value (NTA.dgsíacamsnta). Then UE 301 uses Equation (1) to determine (i.e., compute and / or derive) the TA value for UL transmissions to destination base station 305.

[0097] Option 4 - Depending on certain aspects, the originating base station 305 can indicate to UE 301 (for example, using the TA configuration in transfer command 311) which scenario / type of transfer is used for the non-RACH transfer. For example, the TA configuration in transfer command 311 can indicate whether the non-RACH transfer is an intra-satellite transfer with the same feeder link, an intra-satellite transfer with different feeder links, an inter-satellite transfer with different feeder links, or an inter-satellite transfer with the same feeder links. In some instances, the TA configuration in transfer command 311 can use a Petition 870250088702, dated 09 / 30 / 2025, page 42 / 81 35 / 49 or more parameters to indicate the scenario / type of transfer.

[0098] UE 301 can use the parameters in the TA configuration in the transfer command to determine which TA value parameters UE 301 can reuse from the source PCell's TA value and which TA value parameters UE 301 computes / derives. The source PCell is and / or is associated with source base station 305.

[0099] In some instances, for intra-satellite transfer, the UE 301 can use the UE-specific TA value from the source PCell TA value. UE 301 can compute / derive the other parameters (e.g., the initial time alignment value ( / VT4), the common TA value and the TA offset value (^.^5^™««^)). Then, UE 301 can use Equation (1) to determine (e.g., compute and / or derive) the TA value for UL transmissions to destination base station 305.

[00100] In some examples, for inter-satellite transfer, UE 301 computes / derives the specific UE TA value (AT^adJ). UE 301 can compute / derive the other parameters (e.g., the initial time alignment value (jvrj, the common TA value (A^™™) and the TA offset value ( / VrAd„ÍDCan!i?nrü)). Then, UE 301 can use Equation (1) to determine (e.g., compute and / or derive) the TA value for UL transmissions to the destination base station 305.

[00101] In some examples, for the same feeder link transfer, the UE 301 may use the common TA value ( / V^™”™) of the source PCell's TA value. The UE 301 may compute / derive the other parameters (e.g., the initial time alignment value). Petition 870250088702, dated 09 / 30 / 2025, page 43 / 81 36 / 49 ciai (JVrJ, the specific TA value of UE and the TA offset value (A^,dMfacflnji?nrü)). Then, UE 301 can use Equation (1) to determine (i.e., compute and / or derive) the TA value for UL transmissions to destination base station 305.

[00102] In some examples, for the transfer of different feeder links, UE 301 computes / derives the common TA value. The UE 301 can compute / derive the other parameters (e.g., the initial time alignment value ( / VT4), the UE-specific TA value ( / v^ad7) and the TA offset value. Then UE 301 can use Equation (1) to determine (e.g., compute and / or derive) the TA value for UL transmissions to destination base station 305.

[00103] Depending on some aspects, different options discussed above can be used with different scenarios / types of transfer.

[00104] In a non-limiting example, if the non-RACH transfer is an intra-satellite transfer on the same feeder link, options 1, 2, and / or 4 can be used, as these options can help UE 301 ignore all or part of the TA value calculation. For example, with option 1, the originating base station 303 can indicate that the TA value of the originating PCell can be reused for the destination base station 305. With option 2, the originating base station 303 can set all the parameters of the TA value to be the same as the corresponding parameters of the originating PCell's TA value. With option 4, the originating base station 305 can indicate that the non-RACH transfer is an intra-satellite transfer on the same feeder link.

[00105] In another non-limiting example, if the transfer without Petition 870250088702, dated 09 / 30 / 2025, p. 44 / 81 37 / 49 For an intra-satellite transfer with different feeder links, options 2 and 4 can be used. For example, with option 2, the originating base station can indicate that the initial time alignment value and the specific EU TA value (%) of the TA value for the destination base station 305 are the same as the corresponding parameters of the originating PCell's TA value. With option 4, the originating base station 305 can indicate that the transfer without RACH is an intra-satellite transfer with different feeder links.

[00106] In another non-limiting example, if the non-RACH transfer is a transfer between satellites with different feeder links, options 3 and 4 can be used. For example, with option 3, the originating base station 305 does not indicate any parameter in the TA configuration and UE 301 will perform the TA determination (e.g., computation and / or derivation) according to Equation (1). With option 4, the originating base station 305 can indicate that the non-RACH transfer is a transfer between satellites with different feeder links.

[00107] In another non-limiting example, if the non-RACH transfer is a transfer between satellites with the same feeder link, options 2 and 4 can be used. For example, with option 2, the originating base station can indicate that the common TA value of the destination base station 305 is the same as the corresponding parameter of the TA value of the originating PCell. With option 4, the originating base station 305 can indicate that the non-RACH transfer is a transfer between satellites with the same feeder link.

[00108] However, aspects of this invention are not limited to these examples and other options 1 to 4 may be applied to different Petition 870250088702, dated 09 / 30 / 2025, p. 45 / 81 38 / 49 current scenarios / types of transfer.

[00109] Figure 4 illustrates an example method 400 for a system (e.g., a UE) that implements mechanisms for RACH-free transfer to NTN, according to some aspects of the invention. As a convenience and not a limitation, Figure 4 can be described in relation to the elements of Figures 1 and 3. Method 400 can represent the operation of an electronic device (e.g., UE 103 of Figure 1A and / or UE 301 of Figure 3) that implements mechanisms for RACH-free transfer to NTN. Method 400 can also be implemented by system 200 of Figure 2 and / or computer system 600 of Figure 6. But method 400 is not limited to the specific aspects represented in these figures, and other systems can be used to implement the method, as will be understood by those skilled in the art. It should be considered that not all operations may be necessary, and the operations may not be performed in the same order as shown in Figure 4.

[00110] In 402, a transfer command is received from the originating base station. For example, a UE (e.g., UE 301) receives a transfer command from the originating base station (e.g., originating base station 303) to perform a random access channel-free transfer (RACH) operation to a destination base station (e.g., destination base station 305). In some respects, the transfer command may include a time advance (TA) setting.

[00111] In 404, a TA value is determined based on the TA setting of the transfer command. For example, the UE can determine (e.g., compute and / or derive), based on the TA setting of the transfer command, the TA value for uplink transmission (UL) to the destination base station. Depending on some aspects, the UE can use one or more options. Petition 870250088702, dated 09 / 30 / 2025, pp. 46 / 81 39 / 49 tions 1 to 4 discussed above to determine (e.g., compute and / or derive) the TA value for UL transmissions to the destination base station.

[00112] In some respects (e.g., option 1), the TA setting indicates that a TA value associated with the source base station should be used. In this example, determining the TA value for UL transmission to the destination base station operating 404 may include determining the TA value associated with the source base station and using the TA value associated with the source base station as the TA value for UL transmission to the destination base station. In some respects, determining the TA value associated with the source base station may include determining the TA value associated with the source base station that the UE was using when the UE was communicating with the source base station.

[00113] In some respects (e.g., option 2), the TA setting indicates one or more parameters of a TA value associated with the source base station that should be used. In this example, determining the TA value for UL transmission to the destination base station of operation 404 may include determining one or more parameters of the TA value associated with the source base station and using one or more parameters of the TA value associated with the source base station to compute the TA value for UL transmission to the destination base station. In some respects, determining one or more parameters of the TA value associated with the source base station may include determining one or more parameters of the TA value associated with the source base station that the UE was using when the UE was communicating with the source base station.

[00114] As discussed above in relation to option 2, one or more parameters of the TA value associated with the originating base station Petition 870250088702, dated 09 / 30 / 2025, page 47 / 81 40 / 49 values ​​that must be used comprise one or more of a common TA value, a specific EU TA value, or an initial time alignment value.

[00115] According to some aspects (option 3), the TA configuration indicates the transfer without RACH without providing information regarding the TA value for UL transmission to the destination base station. In this example, determining the TA value for UL transmission to the destination base station of the 404 operation may include assuming that an initial time alignment value has a value of 0 and computing a common TA value, a UE-specific TA value, and a TA offset value. The 404 operation may also include using the initial time alignment value, the common TA value, the UE-specific TA value, and the TA offset value to compute the TA value for UL transmission to the destination base station.

[00116] According to some aspects (option 4), the TA setting indicates a transfer type that is used for non-RACH transfer. In this example, determining the TA value for UL transmission to the destination base station of operation 404 may involve computing the TA value for UL transmission to the destination base station based on the transfer type indicated in the TA setting.

[00117] In 406, an initial UL transmission to the destination base station is performed using the determined TA value. For example, the UE transmits the initial UL transmission to the destination base station based on the determined TA value. The initial transmission may include a complete transfer message, packets / data frames, or similar.

[00118] On 408, a reply message is received from the base station. For example, the UE receives, from the destination base station, the Petition 870250088702, dated 09 / 30 / 2025, pp. 48 / 81 41 / 49 reply message confirming the transfer without RACH.

[00119] In 410, data transmission is performed using the TA value determined in response to the received reply message. For example, the UE performs data transmission to the destination base station based on the determined TA value. Data transmission may include the transmission of data packets / frames, control packets / frames, or similar.

[00120] Figure 5 illustrates an example method 500 for a system (e.g., a base station) that performs mechanisms for non-RACH to NTN transfer, according to some aspects. As a convenience and not a limitation, Figure 5 can be described in relation to the elements of Figures 1 and 4. Method 500 can represent the operation of an electronic device (e.g., base station 101 of Figure 1A and / or origin base station 303 of Figure 3) performing mechanisms for non-RACH to NTN transfer. Method 500 can also be performed by system 200 of Figure 2 and / or computer system 600 of Figure 6. But method 500 is not limited to the specific aspects represented in these figures, and other systems can be used to perform the method, as will be understood by those skilled in the art. It should be considered that not all operations may be necessary, and the operations may not be performed in the same order as shown in Figure 5.

[00121] In 502, an NTN configuration from a destination base station is transmitted to a UE. For example, a source base station (e.g., source base station 303) transmits the NTN configuration of the destination base station (e.g., destination base station 305) to the UE (e.g., UE 301). The NTN configuration might be NTN configuration 309 in Figure 3 and might include a SIB19. SIB19 might include frequency information. Petition 870250088702, dated 09 / 30 / 2025, p. 49 / 81 42 / 49 and RAT priority to be used in the destination cell associated with destination base station 305.

[00122] In some respects, before transmitting the NTN configuration, the originating base station and the destination base station may perform preparation operation(s) for the non-RACH transfer. The preparation operation(s) for the non-RACH transfer may include the non-RACH transfer preparation 307 of Figure 3. The preparation operation(s) for the non-RACH transfer may include, but are not limited to, receiving UE measurement(s), sending a transfer request to the destination base station, and receiving a transfer request response from the destination base station.

[00123] In 504, a TA configuration is determined for the destination base station. For example, the originating base station can determine the TA configuration for the destination base station. In some respects, the originating base station can determine the TA configuration based on the destination base station's NTN configuration. Additionally or alternatively, the originating base station can determine the TA configuration based on pre-configured information for non-RACH transfer. The originating base station can use other methods to determine the TA configuration.

[00124] According to some aspects (e.g., option 1), the originating base station can determine and configure the TA setting so that the TA setting indicates that a TA value associated with the originating base station should be used by the UE.

[00125] According to some aspects (for example, option 2), the originating base station can determine and configure the TA configuration so that the TA configuration indicates one or more parameters of a TA value associated with the originating base station that Petition 870250088702, dated 09 / 30 / 2025, pp. 50 / 81 43 / 49 are to be used by the UE. As discussed above in relation to option 2, the one or more parameters of the TA value associated with the originating base station that must be used comprise one or more of a common TA value, a UE-specific TA value, or an initial time alignment value.

[00126] According to some aspects (option 3), the originating base station can determine and configure the TA setting so that the TA setting indicates the transfer without RACH without providing information regarding the TA value for the UE UL transmission to the destination base station.

[00127] According to some aspects (option 4), the originating base station can determine and configure the TA configuration so that the TA configuration indicates a type of transfer that is used for the transfer without RACH.

[00128] After determining and configuring the TA configuration, the originating base station can generate a transfer command that includes the TA configuration. In 506, the transfer command is transmitted to the UE. For example, the originating base station transmits the transfer command to the UE, where the transfer command includes the TA configuration to be used by the UE to determine a TA value.

[00129] Several aspects can be implemented, for example, using one or more computer systems, such as computer system 600 shown in Figure 6. Computer system 600 can be any computer capable of performing the functions described here, such as devices 101, 103, 104, 121, 131, 134 and 144 from Figures 1A to 1E, 200 from Figure 2 and / or 301, 303, 305 from Figure 3. Computer system 600 includes one or more processors (also called central processing units (CPUs)), such as processor 604. Processor 604 is Petition 870250088702, dated 09 / 30 / 2025, pp. 51 / 81 44 / 49 connected to a communication infrastructure 606 (e.g., a bus). The computer system 600 also includes user input / output device(s) 603, such as monitors, keyboards, pointing devices, etc., which communicate with the communication infrastructure 606 through the user input / output interface(s) 602. The computer system 600 also includes a main or primary memory 608, such as random access memory (RAM). The main memory 608 may include one or more levels of cache. The main memory 608 has control logic (e.g., computer software) and / or data stored in it.

[00130] The computer system 600 may also include one or more secondary storage devices or memory 610. Secondary memory 610 may include, for example, a hard disk drive 612 and / or a removable storage device or unit 614. The removable storage unit 614 may be a floppy disk drive, a magnetic tape drive, a compact disk drive, an optical storage device, a tape backup device and / or any other storage device / unit.

[00131] Removable storage unit 614 can interact with removable storage unit 618. Removable storage unit 618 includes a computer-readable or usable storage device that has computer software (control logic) and / or data stored on it. Removable storage unit 618 can be a floppy disk, a magnetic tape, a compact disc, a DVD, an optical storage disc, and / or any other computer data storage device. Removable storage unit 614 reads and / or writes to removable storage unit 618 in a well-known manner. Petition 870250088702, dated 09 / 30 / 2025, pp. 52 / 81 45 / 49

[00132] In some respects, secondary memory 610 may include other means, other devices or other approaches to enable computer programs and / or other instructions and / or other data to be accessed by the computer system 600. Such means, devices or other approaches may include, for example, a removable storage unit 622 and an interface 620. Examples of the removable storage unit 622 and the interface 620 may include a program cartridge and a cartridge interface (such as that found in video game devices), a removable memory chip (such as an EPROM or a PROM) and associated socket, a memory stick and a USB port, a memory card and associated memory card slot and / or any other removable storage unit and associated interface.

[00133] Computer system 600 may also include a network or communication interface 624. The communication interface 624 enables computer system 600 to communicate and interact with any combination of remote devices, remote networks, remote entities, etc. (individually and collectively referenced by reference number 628). For example, the communication interface 624 may enable computer system 600 to communicate with remote devices 628 along communication path 626, which may use wired and / or wireless connections, and which may include any combination of LANs, WANs, the Internet, etc. Control logic and / or data may be transmitted to and from computer system 600 via communication path 626.

[00134] The operations described above can be implemented in a wide variety of configurations and architectures. Therefore, some or all of the operations described above can be performed in hardware, in software, or in both. In some Petition 870250088702, dated 09 / 30 / 2025, pp. 53 / 81 46 / 49 aspects, a tangible and non-transitory manufactured apparatus or article that includes a tangible and non-transitory usable or computer-readable medium that has control logic (software) stored thereon is also referred to in the present invention as a computer program product or program storage device. This includes, but is not limited to, a computer system 600, a main memory 608, a secondary memory 610, and removable storage units 618 and 622, as well as tangible manufactured articles incorporating any combination of the aforementioned items. Such control logic, when executed by one or more data processing devices (such as the computer system 600), causes those data processing devices to operate as described herein.

[00135] Based on the teachings contained in this invention, it will be evident to those skilled in the relevant art(s) how to develop and use aspects of the invention with the use of data processing devices, computer systems and / or computer architectures other than those shown in Figure 6. In particular, the aspects may operate with software, hardware and / or operating system implementations beyond those described herein.

[00136] It should be noted that the 'Detailed Description' section, and not the Summary and Abstract sections, is intended to be used for interpreting the claims. The Summary and Abstract sections may present one or more, but not all, exemplary aspects of the invention and, therefore, are not intended to limit the invention or the appended claims in any way.

[00137] Although the invention has been described herein with reference to exemplary aspects for exemplary applications and fields, it should be understood that the invention is not limited to this. Other aspects and modifications thereof are possible and are Petition 870250088702, dated 09 / 30 / 2025, pp. 54 / 81 47 / 49 within the scope and spirit of the invention. For example, and without limiting the generality of this paragraph, the aspects are not limited to the software, hardware, firmware and / or entities illustrated in the figures and / or described herein. Furthermore, the aspects (whether or not explicitly described herein) have significant utility for fields and applications beyond the examples described herein.

[00138] The aspects described here have been used with the aid of functional structural units that illustrate the implementation of specific functions and their relationships. The boundaries of these functional structural units have been arbitrarily defined here for the convenience of the description. Alternative boundaries may be defined, provided that the specified functions and relationships (or their equivalents) are adequately realized. Furthermore, alternative aspects may implement functional blocks, steps, operations, methods, etc., using orderings different from those described here.

[00139] References in the present invention to an aspect, aspects, an example, examples, or similar phrases indicate that the aspect(s) described may include a particular feature, structure, or characteristic, but each aspect may not necessarily include the particular feature, structure, or characteristic. Furthermore, such phrases do not necessarily refer to the same aspect. Additionally, when a specific feature, structure, or characteristic is described in connection with an aspect, it would be within the knowledge of those skilled in the relevant art(s) to incorporate such feature, structure, or characteristic into other aspects, whether or not they are explicitly mentioned or described herein.

[00140] The scope and extent of the invention shall not be limited by any of the exemplary aspects described above, but shall be defined only in accordance with the claims and Petition 870250088702, dated 09 / 30 / 2025, pages 55 / 81 48 / 49 and their equivalents below.

[00141] The present invention contemplates that entities responsible for collecting, analyzing, processing, transferring, storing, or otherwise using such personal information data will adhere to well-established privacy policies and / or practices. In particular, these entities must implement and consistently use privacy policies and practices that are generally recognized as meeting or exceeding industry or government requirements for keeping personal information data private and secure. Such policies must be easily accessible to users and must be updated as changes in data collection and / or use occur. Users' personal information must be collected for the entity's legitimate and reasonable uses and not shared or sold outside the scope of such legitimate uses.Additionally, such collection / sharing should only occur after receiving informed consent from users. Furthermore, these entities should consider taking any necessary measures to safeguard and protect access to this personal information data and ensure that others with access to personal information data comply with their privacy policies and procedures. Additionally, these entities may submit to a third-party assessment to certify their compliance with widely accepted privacy policies and practices. Moreover, policies and practices should be tailored to the specific types of personal information data that are collected and / or accessed and should adapt to applicable laws and standards, including jurisdiction-specific considerations.For example, in the US, the collection of or access to certain health data may be regulated by federal and / or state laws, such as the Health Insurance Portability and Accountability Act (HIPAA). Petition 870250088702, dated 09 / 30 / 2025, pp. 56 / 81 49 / 49 Accountability Act); whereas in other countries, health data may be subject to different regulations and policies and must be handled appropriately. Therefore, different privacy practices must be maintained for different types of personal data in each country.

Claims

CLAIMS 1. User equipment (UE), characterized by comprising: a transceiver configured to enable wireless communication with a source base station; and a processor communicatively coupled to the transceiver and configured to: receive, using the transceiver and from the source base station, a transfer command to perform a random access channel-free transfer (RACH) operation to a destination base station, wherein the transfer command comprises a time advance (TA) setting; determine, based on the TA setting of the transfer command, a TA value for uplink (UL) transmission to the destination base station; and transmit, using the transceiver and to the destination base station, an initial UL transmission based on the determined TA value.

2. UE, according to claim 1, characterized in that the TA setting indicates that a TA value associated with the originating base station should be used, and in which, to determine the TA value for UL transmission to the destination base station, the processor is configured to: determine the TA value associated with the originating base station; and use the TA value associated with the originating base station as the TA value for UL transmission to the destination base station.

3. UE, according to claim 1, characterized in that the TA configuration indicates one or more parameters of a TA value associated with the originating base station that must be used, and in which, to determine the TA value for UL transmission to the destination base station, the processor is configured to: determine one or more parameters of the TA value associated with the originating base station; and use one or more parameters of the TA value associated with the originating base station to compute the TA value for UL transmission to the destination base station.

4. UE, according to claim 3, characterized in that one or more parameters of the TA value associated with the originating base station that are to be used comprise one or more of a common TA value, a UE-specific TA value, or an initial time alignment value.

5. UE, according to claim 1, characterized in that the TA configuration indicates the transfer without RACH without providing information regarding the TA value for UL transmission to the destination base station, and wherein, to determine the TA value for UL transmission to the destination base station, the processor is configured to: assume that an initial time alignment value has a value of 0; compute a common TA value, a UE-specific TA value, and a TA offset value; and use the initial time alignment value, the common TA value, the UE-specific TA value, and the TA offset value to compute the TA value for UL transmission to the destination base station.

6. UE, according to claim 1, characterized in that the TA configuration indicates a type of transfer that is used for non-RACH transfer, and in which, to determine the TA value Petition 870250088702, dated 09 / 30 / 2025, page 59 / 81 3 / 7 for UL transmission to the destination base station, the processor is configured to: compute the TA value for UL transmission to the destination base station based on the type of transfer indicated in the TA configuration.

7. UE, according to claim 1, characterized in that the processor is further configured to: receive, using the transceiver and from the destination base station, a reply message confirming the transfer without RACH; and perform the data transmission to the destination base station based on the determined TA value.

8. A method performed by a user device (UD), characterized by comprising: receiving, from the originating base station, a transfer command to perform a random access channel-free transfer (RACH) operation to a destination base station, wherein the transfer command comprises a time advance (TA) setting; determining, based on the TA setting of the transfer command, a TA value for uplink transmission (UL) to the destination base station; and transmitting, to the destination base station, an initial UL transmission based on the determined TA value.

9. Method according to claim 8, characterized in that the TA setting indicates that a TA value associated with the originating base station should be used, and wherein the determination of the TA value for UL transmission to the destination base station comprises: determining the TA value associated with the originating base station; and using the TA value associated with the originating base station as the TA value for UL transmission to the destination base station.

10. A method according to claim 8, characterized in that the TA configuration indicates one or more parameters of a TA value associated with the originating base station that must be used, and wherein the determination of the TA value for UL transmission to the destination base station comprises: determining the one or more parameters of the TA value associated with the originating base station; and using the one or more parameters of the TA value associated with the originating base station to compute the TA value for UL transmission to the destination base station.

11. Method, according to claim 10, characterized in that the one or more parameters of the TA value associated with the origin base station that are to be used comprise one or more of a common TA value, a UE-specific TA value, or an initial time alignment value.

12. Method according to claim 8, characterized in that the TA setting indicates the transfer without RACH without providing information regarding the TA value for UL transmission to the destination base station, and wherein the determination of the TA value for UL transmission to the destination base station comprises: assuming that an initial time alignment value has a value of 0; computing a common TA value, a UE-specific TA value and a TA offset value; and using the initial time alignment value, the common TA value, the UE-specific TA value and the TA offset value to compute the TA value for UL transmission to the destination base station.

13. Method, according to claim 8, characterized in that the TA setting indicates a type of transfer that is used for non-RACH transfer, and wherein the determination of the TA value for UL transmission to the destination base station comprises: computing the TA value for UL transmission to the destination base station based on the type of transfer indicated in the TA setting.

14. Method, according to claim 8, further characterized by comprising: receiving, from the destination base station, a reply message confirming the transfer without RACH; and performing the data transmission to the destination base station based on the determined TA value.

15. Non-transient, computer-readable media, characterized by storing instructions that, when executed by a user equipment (UE) processor, cause the UE to perform operations comprising: receiving, from the originating base station, a transfer command to perform a random access channel-free transfer (RACH) operation to a destination base station, wherein the transfer command comprises a time advance (TA) setting; determining, based on the TA setting of the transfer command, a TA value for uplink (UL) transmission to the destination base station; transmitting, using the transceiver and to the base station of Petition 870250088702, dated 09 / 30 / 2025, p.62 / 81 6 / 7 destination, an initial UL transmission based on the determined TA value; receive, from the destination base station and in response to the initial UL transmission, a response message confirming the transfer without RACH; and perform the data transmission to the destination base station based on the determined TA value.

16. Computer-readable non-transient media according to claim 15, characterized in that the TA setting indicates that a TA value associated with the originating base station should be used, and wherein the determination of the TA value for UL transmission to the destination base station comprises: determining the TA value associated with the originating base station; and using the TA value associated with the originating base station as the TA value for UL transmission to the destination base station.

17. Computer-readable non-transient media according to claim 15, characterized in that the TA configuration indicates one or more parameters of a TA value associated with the originating base station that are to be used, and wherein the determination of the TA value for UL transmission to the destination base station comprises: determining the one or more parameters of the TA value associated with the originating base station; and using the one or more parameters of the TA value associated with the originating base station to compute the TA value for UL transmission to the destination base station.

18. Non-transient computer-readable media according to claim 17, characterized in that one or more parameters of the TA value associated with the originating base station that must be used comprise one or more of a common TA value, a UE-specific TA value, or an initial time alignment value.

19. Computer-readable non-transient media according to claim 15, characterized in that the TA setting indicates non-RACH transfer without providing information regarding the TA value for UL transmission to the destination base station, and wherein the determination of the TA value for UL transmission to the destination base station comprises: assuming that an initial time alignment value has a value of 0; computing a common TA value, a UE-specific TA value, and a TA offset value; and using the initial time alignment value, the common TA value, the UE-specific TA value, and the TA offset value to compute the TA value for UL transmission to the destination base station.

20. Computer-readable non-transient media according to claim 15, characterized in that the TA setting indicates a transfer type that is used for non-RACH transfer, and wherein the determination of the TA value for UL transmission to the destination base station comprises: computing the TA value for UL transmission to the destination base station based on the transfer type indicated in the TA setting.

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