Uplink synchronization processing method and apparatus for satellite handover in wireless communications

Abstract

An uplink synchronization processing method and apparatus for satellite handover in wireless communications are provided. Accordingly, the user equipment may handle uplink synchronization of satellite handover, thereby avoiding a decrease in transmission efficiency. The user equipment may also appropriately process resources and / or configurations during satellite handover. A method for a user equipment includes receiving an indication of uplink synchronization loss from an upper layer; and in response to receiving the indication of uplink synchronization loss: not performing uplink transmissions on the serving cell; and determining whether to clear the one or more hybrid automatic repeat request buffers based on whether the uplink synchronization loss is caused by the satellite handover.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefit of U.S. Provisional Patent Application No. 63 / 537,728 filed on September 11, 2023, U.S. Provisional Patent Application No. 63 / 537,759 filed on September 11, 2023, and U.S. Provisional Patent Application No. 63 / 545,290 filed on October 23, 2023; each of the cited applications and publications being incorporated herein by reference in their entirety. Technical Field

[0003] The present disclosure relates generally to wireless communication networks, and more particularly, to methods and apparatus for uplink (UL) synchronization processing for satellite handover in wireless communication systems. Background Art

[0004] With the rapid growth of the demand for transmitting large amounts of data to and from mobile communication devices, traditional mobile voice communication networks have evolved into networks that communicate using Internet Protocol (IP) packets. Such IP packet communications can provide IP-bearing voice, multimedia, multicast and on-demand communication services to users of mobile communication devices.

[0005] An exemplary network structure is the Evolved Universal Terrestrial Radio Access Network (E-UTRAN). The E-UTRAN system can provide high data throughput to implement the above-mentioned IP-borne voice and multimedia services. rd The 3GPP (3rd Generation Partnership Project) standards organization is discussing new next generation (e.g., 5G) radio technologies. Therefore, changes to the current body of 3GPP standards are currently being submitted and considered to enable the 3GPP standards to evolve and be completed. Summary of the invention

[0006] Provided are a method, system and device for uplink (UL) synchronization processing for satellite handover in a wireless communication system. Therefore, a user equipment (UE) can handle UL synchronization for satellite handover, thereby avoiding reducing transmission efficiency. The UE can also properly handle resources and / or configuration during satellite handover.

[0007] In various embodiments, a method for a UE in a wireless communication system includes: receiving an indication of uplink synchronization loss from an upper layer; and in response to receiving the indication of uplink synchronization loss: not performing uplink transmission on a serving cell, and determining whether to clear one or more Hybrid Automatic Repeat Request (HARQ) buffers based on whether the uplink synchronization loss is caused by satellite switching.

[0008] In various embodiments, a method for a UE in a wireless communication system includes: receiving system information, wherein the system information includes at least a first non-terrestrial network (NTN) configuration, time information, and an indication of satellite switching; in response to receiving the system information, starting or restarting a timer based on the first NTN configuration; initiating a satellite switching procedure based on the indication of satellite switching being included in the system information; stopping the timer immediately after a timing indicated by the time information; after stopping the timer, considering that uplink (UL) synchronization has been lost; determining whether to clear one or more HARQ buffers based on whether the UL synchronization is lost due to satellite switching; performing downlink (DL) synchronization with a cell served by a satellite indicated in the indication of satellite switching; after performing DL synchronization, starting a timer based on a second NTN configuration included in the indication of satellite switching; and after starting the timer, considering that UL synchronization has been obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 The drawings show a wireless communication system according to an embodiment of the present invention.

[0010] Figure 2 is a block diagram of a transmitter system (also referred to as an access network) and a receiver system (also referred to as a user equipment or UE) according to an embodiment of the present invention.

[0011] Figure 3 is a functional block diagram of a communication system according to an embodiment of the present invention.

[0012] Figure 4 According to an embodiment of the present invention Figure 3 Functional block diagram of the program code.

[0013] Figure 5 It is in 3GPP TS 38.300V17.5.0 Fig.16 .14.1-1: Reproduction of the overall diagram of NTN.

[0014] Figure 6 It is in 3GPP TS 38.300V17.5.0 Fig.16.Reproduction of the diagram of the timing relationship of .14.2.1-1 (for collocated gNB and NTN Gateway).

[0015] Figure 7 It is in 3GPP TS 38.211V17.5.0 Figure 4 .3.1-1: Re-enactment of uplink-downlink timing association.

[0016] Figure 8 It is in 3GPP TS 38.321V17.5.0 Figure 6 .1.3.4-1: Reappearance of timing advance command MAC CE.

[0017] Fig. 9 It is in 3GPP TS 38.321V17.5.0 Figure 6 .1.3.56-1: Reappearance of the timing advance reporting MAC CE.

[0018] Fig.10 It is in 3GPP TS 38.331V17.5.0 Figure 5 .3.3.1-1: Reproduction of RRC connection establishment (success).

[0019] Fig.11 It is in 3GPP TS 38.331V17.5.0 Figure 5 .3.5.1-1: Reproduction of RRC reconfiguration (successful).

[0020] Fig.12 It is in 3GPP TS 38.331V17.5.0 Figure 5 .3.5.1-2: Recurrence of RRC reconfiguration (failure).

[0021] Fig.13 It is in 3GPP TS 38.331V17.5.0 Figure 5 .3.7.1-1: Re-establishment of RRC connection (success).

[0022] Fig.14 It is in 3GPP TS 38.331V17.5.0 Figure 5 .3.7.1-2: RRC re-establishment falls back to re-establishment of RRC establishment (success).

[0023] Fig.15 It is in 3GPP TS 38.331V17.5.0 Figure 5 .3.13.1-1: Reproduction of RRC connection recovery (success).

[0024] Fig.16It is in 3GPP TS 38.331V17.5.0 Figure 5 .3.13.1-2: RRC connection recovery falls back to the reappearance of RRC connection establishment (success).

[0025] Fig.17 FIG. 1 is an exemplary diagram of satellite switching according to an embodiment of the present invention.

[0026] Fig.18 1 is a flowchart of a method of a UE according to an embodiment of the present invention, the method comprising: receiving a first indication of satellite switching; performing DL synchronization with a serving cell at a timing; receiving NTN-specific system information; after performing DL synchronization with the serving cell, determining whether to trigger a TA report based on whether the indication is provided by a network; and triggering a TA report if the indication is provided by the network in the NTN-specific system information.

[0027] Fig.19 The present invention is a flowchart of a method of a UE according to an embodiment of the present invention, the method comprising: receiving a configuration of a satellite switching; initiating a satellite switching at a timing; in response to the satellite switching, performing DL and / or UL (re)synchronization with a serving cell; in response to the satellite switching, reacquiring system information related to an NTN; and in response to the satellite switching, not considering that a time alignment timer has expired.

[0028] Fig. 20 FIG. 1 is an exemplary diagram of hard satellite switching according to an embodiment of the present invention.

[0029] Fig.21 FIG. 1 is an exemplary diagram of hard satellite switching according to an embodiment of the present invention.

[0030] Fig. 22 FIG. 1 is an exemplary diagram of soft satellite switching according to an embodiment of the present invention.

[0031] Fig.23 FIG. 1 is an exemplary diagram of soft satellite switching according to an embodiment of the present invention.

[0032] Fig.24 FIG. 1 is a diagram illustrating an example of UL synchronization processing of satellite switching according to an embodiment of the present invention.

[0033] Fig.25The present invention is a flowchart of a method of a UE, the method comprising: receiving a first indication of satellite switching; receiving an NTN configuration of a target satellite; performing DL synchronization with the target satellite at a timing; in response to performing DL synchronization with the target satellite, stopping an UL synchronization timer for a serving cell; after the UL synchronization timer is stopped, starting an UL synchronization timer for the serving cell based on the NTN configuration of the target satellite; based on the NTN configuration of the target satellite being available, not considering the UL synchronization timer to have expired at t-Service; and performing an RA procedure for satellite switching while the UL synchronization timer is running.

[0034] Fig.26 The present invention is a flow chart of a method of a UE, the method comprising: receiving an indication of uplink synchronization loss from an upper layer; and in response to receiving the indication of uplink synchronization loss: not performing uplink transmission on a serving cell, and determining whether to clear one or more HARQ buffers based on whether the uplink synchronization loss is caused by satellite switching.

[0035] Fig. 27 The invention is a flowchart of a method of a UE, the method comprising: receiving system information, wherein the system information includes at least a first NTN configuration, time information, and an indication of satellite switching; in response to receiving the system information, starting or restarting a timer based on the first NTN configuration; initiating a satellite switching procedure based on the indication of satellite switching being included in the system information; stopping the timer immediately after a timing indicated by the time information; after stopping the timer, considering that UL synchronization has been lost; determining whether to clear one or more HARQ buffers based on whether the UL synchronization is lost due to satellite switching; performing DL synchronization with a cell served by a satellite indicated in the indication of satellite switching; after performing DL synchronization, starting a timer based on a second NTN configuration included in the indication of satellite switching; and after starting the timer, considering that UL synchronization has been obtained. DETAILED DESCRIPTION

[0036] The present invention described herein may be applied to or implemented in the exemplary wireless communication systems and devices described below. In addition, the present invention is mainly described in the context of the 3GPP architecture reference model. However, it should be understood that with the help of the disclosed information, those skilled in the art can easily adapt to use and implement various aspects of the present invention in the 3GPP2 network architecture as well as other network architectures.

[0037] The exemplary wireless communication systems and devices described below employ wireless communication systems that support broadcast services. Wireless communication systems are widely deployed to provide various types of communications, such as voice, data, and the like. These systems may be based on code division multiple access (CDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), 3GPP Long Term Evolution (LTE) radio access, 3GPP Long Term Evolution Advanced (LTE-A), 3GPP2 Ultra Mobile Broadband (UMB), WiMax, 3GPP New Radio (NR), or some other modulation techniques.

[0038] Specifically, the exemplary wireless communication systems and devices described below can be designed to support one or more standards, such as standards provided by an association named "3rd Generation Partnership Project" (referred to herein as 3GPP), including: [1] 3GPP TS 38.300 V17.5.0, "NR, NR and NG-RAN Overview, Stage 2"; [2] 3GPP TS 38.211 V17.5.0, "NR, Physical Channels and Modulation"; [3] 3GPP TS 38.321 V17.5.0, "NR, MAC Protocol Specification"; [4] 3GPP TS 38.331 V17.5.0, "NR, RRC Protocol Specification"; [5] R2-2309341, "RRC Protocol Specification for NR NTN Rel-18"; [6] 3GPP TS 38.300 V17.5.0, "NR, NR and NG-RAN Overview, Stage 2"; [7] 3GPP TS 38.211 V17.5.0, "NR, Physical Channels and Modulation"; [8] 3GPP TS 38.321 V17.5.0, "NR, MAC Protocol Specification"; [9] 3GPP TS 38.331 V17.5.0, "NR, RRC Protocol Specification";

[10] R2-2309341, "RRC Protocol Specification for NR NTN Rel-18";

[11] [6] R2-2308373, “Satellite Handover: PCI Change without L3 Handover”, NEC; [7] R2-2304273, “LS on Unchanged PCI”; [8] R2-2307623, “Details on Satellite Handover with Unchanged PCI”, Qualcomm; [9] 3GPP TS 38.331V17.6.0, NR, RRC Protocol Specification; and

[10] R2-2310307, ​​“Satellite Handover with Unchanged PCI”, Apple. The standards and documents listed above are hereby expressly and entirely incorporated herein by reference in their entirety.

[0039] Figure 11 shows a multiple access wireless communication system according to an embodiment of the present invention. An access network 100 (AN) includes multiple antenna groups, one of which includes antenna groups 104 and 106, another includes antenna groups 108 and 110, and another includes antenna groups 112 and 114. Figure 1 1, only two antennas are shown for each antenna group, however, each antenna group may utilize more or fewer antennas. Access terminal (AT) 116 communicates with antennas 112 and 114, where antennas 112 and 114 transmit information to access terminal 116 via forward link 120 and receive information from AT 116 via reverse link 118. AT 122 communicates with antennas 106 and 108, where antennas 106 and 108 transmit information to AT 122 via forward link 126 and receive information from AT 122 via reverse link 124. In an FDD system, communication links 118, 120, 124, and 126 may use different frequencies for communication. For example, forward link 120 may use a different frequency than the frequency used by reverse link 118.

[0040] Each antenna group and / or the area in which the antenna group is designed to communicate is often referred to as a sector of the access network. In an embodiment, the antenna groups are each designed to communicate with access terminals in a sector of the area covered by the access network 100.

[0041] In communicating over forward links 120 and 126, the transmit antennas of access network 100 may utilize beamforming in order to improve the signal-to-noise ratio of the forward links for the different access terminals 116 and 122. Furthermore, an access network that transmits to access terminals randomly dispersed throughout its coverage area using beamforming typically causes less interference to access terminals in neighboring cells than an access network that transmits to all of its access terminals via a single antenna.

[0042] AN can be a fixed station or base station for communicating with a terminal, and can also be referred to as an access point, Node B, base station, enhanced base station, eNodeB, gNB or some other term. AT can also be referred to as user equipment (UE), a wireless communication device, a terminal, an access terminal or some other term.

[0043] Figure 2 2 is a simplified block diagram of an embodiment of a transmitter system 210 (also referred to as an access network) and a receiver system 250 (also referred to as an access terminal (AT) or user equipment (UE)) in a MIMO system 200. At the transmitter system 210, traffic data for a number of data streams is provided from a data source 212 to a transmit (TX) data processor 214.

[0044] In one embodiment, each data stream is transmitted through a corresponding transmit antenna. TX data processor 214 formats, codes, and interleaves the traffic data for each data stream based on a particular coding scheme selected for that data stream to provide coded data.

[0045] The decoded data for each data stream may be multiplexed with pilot data using OFDM techniques. The pilot data is typically a known data pattern that is processed in a known manner and may be used at the receiver system to estimate the channel response. The multiplexed pilot data and decoded data for each data stream may then be modulated (i.e., symbol mapped) based on a particular modulation scheme (e.g., BPSK, QPSK, M-PK, or M-QAM) selected for the data stream to provide modulation symbols. The data rate, coding, and modulation for each data stream may be determined by instructions executed by the processor 230. The memory 232 is coupled to the processor 230.

[0046] The modulation symbols for all data streams are then provided to a TX MIMO processor 220, which may further process the modulation symbols (eg, for OFDM). The TX MIMO processor 220 then converts the N T The modulation symbol streams are provided to N T 1. Transmitters (TMTRs) 222a through 222t. In certain embodiments, TX MIMO processor 220 applies beamforming weights to the symbols of the data streams and to the antenna from which the symbol is being transmitted.

[0047] Each transmitter 222 receives and processes a corresponding symbol stream to provide one or more analog signals, and further conditions (e.g., amplifies, filters, and upconverts) the analog signals to provide a modulated signal suitable for transmission over the MIMO channel. T The antennas 224a to 224t transmit the N signals from the transmitters 222a to 222t. T a modulated signal.

[0048] At the receiver system 250, N R The transmitted modulated signals are received by each antenna 252a through 252r and the received signal from each antenna 252 is provided to a respective receiver (RCVR) 254a through 254r. Each receiver 254 conditions (e.g., filters, amplifies, and downconverts) a respective received signal, digitizes the conditioned signal to provide samples, and further processes the samples to provide a corresponding “received” symbol stream.

[0049] Next, the RX data processor 260 receives the N R The receiver 254 receives N R symbol streams and processes N based on a particular receiver processing technique R received symbol streams to provide N T The RX data processor 260 then demodulates, deinterleaves, and decodes each detected symbol stream to recover the traffic data for the data stream. The processing by the RX data processor 260 is complementary to the processing performed by the TX MIMO processor 220 and the TX data processor 214 at the transmitter system 210.

[0050] Processor 270 periodically determines which pre-coding matrix to use (discussed below). Processor 270 formulates a reverse link message comprising a matrix index portion and a rank value portion.

[0051] The reverse link message may include various types of information about the communication link and / or the received data stream. The reverse link message is then processed by the TX data processor 238 (which also receives traffic data for a number of data streams from the data source 236), modulated by the modulator 280, conditioned by the transmitters 254a to 254r, and transmitted back to the transmitter system 210.

[0052] At the transmitter system 210, the modulated signal from the receiver system 250 is received by the antenna 224, conditioned by the receiver 222, demodulated by the demodulator 240, and processed by the RX data processor 242 to extract the reverse link message transmitted by the receiver system 250. The processor 230 then determines which precoding matrix to use to determine the beamforming weights and then processes the extracted message.

[0053] Memory 232 may be used to temporarily store some buffered / calculated data from 240 or 242 via processor 230, store some buffered data from 212, or store some specific program code. In addition, memory 272 may be used to temporarily store some buffered / calculated data from 260 via processor 270, store some buffered data from 236, or store some specific program code.

[0054] See instead Figure 3 , this figure shows an alternative simplified functional block diagram of a communication device according to one embodiment of the present invention. Figure 3 As shown in FIG. , the communication device 300 in the wireless communication system can be used to implement Figure 1UE (or AT) 116 and 122 in, and the wireless communication system is preferably an NR system. The communication device 300 may include an input device 302, an output device 304, a control circuit 306, a central processing unit (CPU) 308, a memory 310, a program code 312, and a transceiver 314. The control circuit 306 executes the program code 312 in the memory 310 through the CPU 308, thereby controlling the operation of the communication device 300. The communication device 300 can receive a signal input by a user through the input device 302 (such as a keyboard or a keypad), and can output images and sounds through the output device 304 (such as a monitor or a speaker). The transceiver 314 is used to receive and transmit wireless signals, pass the received signal to the control circuit 306, and wirelessly output the signal generated by the control circuit 306.

[0055] Figure 4 According to an embodiment of the present invention Figure 3 4. In this embodiment, program code 312 includes application layer 400, layer 3 portion 402, and layer 2 portion 404, and is coupled to layer 1 portion 406. Layer 3 portion 402 typically implements radio resource control. Layer 2 portion 404 typically implements link control. Layer 1 portion 406 typically implements physical connectivity.

[0056] For LTE, LTE-A or NR systems, the layer 2 portion 404 may include a radio link control (RLC) layer and a medium access control (MAC) layer. The layer 3 portion 402 may include a radio resource control (RRC) layer.

[0057] Any two or more of the following paragraphs, (sub) bullet points, points, actions or claims described in each invention paragraph or section may be logically, reasonably and appropriately combined to form a specific method.

[0058] Any sentence, paragraph, (sub) bullet, key point, action or claim described in each invention paragraph or section below can be implemented independently and separately to form a specific method or device. The following disclosure of the present invention, such as "based on", "more specifically", "example", etc., is only a possible embodiment that does not limit a specific method or device.

[0059] The general description of Rel-17 NR non-terrestrial network (NTN) is specified in TS 38.300 ([1] 3GPP TS 38.300 V17.5.0) as follows:

[0060] *************************Quote starts [1]************************

[0061] 16.14 Non-terrestrial Networks

[0062] 16.14.1 Overview

[0063] Fig.16 .14.1-1 An example of a non-terrestrial network (NTN) is illustrated below, which provides non-terrestrial NR access to a UE with the help of an NTN payload and an NTN gateway, thereby depicting a service link between the NTN payload and the UE, and a feeder link between the NTN gateway and the NTN payload.

[0064] Figure 5 It is in 3GPP TS 38.300V17.5.0 Fig.16 .14.1-1: Reproduction of the overall diagram of NTN.

[0065] …

[0066] The NTN payload transparently forwards the radio protocol received from the UE (via the serving link) to the NTN Gateway (via the feeder link) and vice versa. The following connectivity is supported by the NTN payload:

[0067] -NTN gateway can serve multiple NTN payloads;

[0068] - NTN payload can be served by multiple NTN gateways.

[0069] …

[0070] Three types of service links are supported:

[0071] - Geofixed: provided by a beam that constantly covers the same geographical area (e.g. the case of GSO satellites);

[0072] - Quasi-geo-fixed: provided by a beam covering one geographical area during a limited period and a different geographical area during another period (e.g. the case of NGSO satellites producing steerable beams);

[0073] - Geomobile: provided by beams whose coverage area slides over the surface of the Earth (e.g. the case of NGSO satellites producing fixed or non-steerable beams).

[0074] Using NGSO satellites, gNBs can provide quasi-geo-fixed service links or geo-mobile service links, while gNBs operated using GSO satellites can provide geo-fixed service links.

[0075] In this release, UEs supporting NTN have GNSS functionality.

[0076] 16.14.2 Timing and Synchronization

[0077] 16.14.2.1 Scheduling and Timing

[0078] DL and UL are aligned at the uplink time synchronization reference point (RP), with N TA，offset Given offset (see clause 4.2 of TS 38.213).

[0079] To accommodate the propagation delay in NTN, a common timing advance (Common TA) and two offsets K offset and k mac To enhance several timing relationships:

[0080] - Common TA is the configured timing offset equal to the RTT between RP and NTN payload.

[0081] -K offset is the configured scheduling offset that needs to be greater than or equal to the sum of the serving link RTT and the common TA.

[0082] -k mac is the configured offset which is roughly equal to the RTT between the RP and the gNB.

[0083] Scheduling offset K offset Used to allow sufficient UE processing time between downlink reception and uplink transmission, see TS 38.213.

[0084] Offset k mac Used to delay the application of the downlink configuration indicated by the MAC CE command on the PDSCH (see TS 38.213) and used in the estimation of the UE-gNB RTT (see TS 38.321 [3]). The offset may be provided by the network when the downlink and uplink frame timings are not aligned at the gNB. mac It is also used in the random access procedure to determine the start time of the RAR window / MsgB window after Msg1 / MsgA transmission (see TS 38.213).

[0085] exist Fig.16.14.2.1-1 describes the service link RTT, feeder link RTT, RP, common TA, k mac and T TA (See clause 16.14.2.2).

[0086] Figure 6 It is in 3GPP TS 38.300V17.5.0 Fig.16 .Reproduction of the diagram of the timing relationship of .14.2.1-1 (for collocated gNB and NTN Gateway).

[0087] …

[0088] 16.14.2.2 Timing Advance and Frequency Precompensation

[0089] For the serving cell, the network broadcasts valid ephemeris information and common TA parameters. The UE shall have a valid GNSS position as well as ephemeris and common TA before connecting to the NTN cell. To achieve synchronization, the UE shall calculate the RTT between the UE and the RP based on the GNSS position, ephemeris and common TA parameters before and during connection to the NTN cell (see clause 4.2 in TS 38.213), and Fig.16 .14.2.1-1 autonomously pre-compensates T for the RTT between UE and RP TA (See clause 4.3 of TS 38.211[2]).

[0090] The UE shall calculate the Doppler shift of the serving link by taking into account the UE position and ephemeris and autonomously pre-compensate for it in uplink transmissions.If the UE does not have a valid GNSS position and / or valid ephemeris and a common TA, the UE shall not transmit until both are reacquired.

[0091] In connected mode, the UE should be able to continuously update the timing advance and frequency pre-compensation.

[0092] The UE may be configured to report the Opportunity Advance during the Random Access procedure or in connected mode. In connected mode, event-triggered reporting of the Opportunity Advance is supported.

[0093] ********************END OF QUOTE****************************

[0094] The general description of timing advance (TA) is specified in TS 38.300 ([1] 3GPP TS 38.300 V17.5.0) as follows:

[0095] ******************** Quote starts [1]************************

[0096] 9.2.9 Early Timing

[0097] In RRC_CONNECTED, the gNB is responsible for maintaining the timing advance to keep L1 synchronized. Serving cells with the same UL timing advance and using the same timing reference cell are grouped in one TAG. Each TAG contains at least one serving cell with configured uplink, and the mapping of each serving cell to a TAG is configured by RRC.

[0098] For the primary TAG, the UE uses the PCell as the timing reference, but will share the spectrum channel access, where in some cases the SCell can also be used (see clause 7.1 of TS 38.133). In the secondary TAG, the UE can use any of the activated Scells of this TAG as the timing reference cell, but should not change the timing reference cell unless necessary.

[0099] The timing advance update is delivered by the gNB to the UE via a MAC CE command. Such a command restarts a TAG specific timer which indicates whether L1 can be synchronized: when the timer is running, L1 is considered to be synchronized, otherwise, L1 is considered to be out of sync (in this case, uplink transmissions can only occur via MSG1 / MSGA).

[0100] *************************END OF QUOTE********************

[0101] TA information including definitions and formulas for calculating TA parameters is specified in TS 38.211 ([2] 3GPP TS 38.211 V17.5.0) as follows:

[0102] ******************** Quote starts [2]********************

[0103] 4.3 Frame Structure

[0104] 4.3.1 Frame and Subframe

[0105] Downlink, uplink and sidelink transmissions are organized into f =(Df max N f / 100)·T c = 10ms duration frame, each frame consists of T sf =(Dfmax N f / 1000)·T c =1 ms duration. The number of consecutive OFDM symbols per subframe is Each frame is divided into two equally sized half-frames, each half-frame having five sub-frames, where half-frame 0 consists of sub-frames 0-4 and half-frame 1 consists of sub-frames 5-9.

[0106] On a carrier, there is one set of frames in the uplink and one set of frames in the downlink.

[0107] The uplink frame number i for transmissions from a UE will start before the start of the corresponding downlink frame at the UE in

[0108] -N TA and N TA，offset Given by clause 4.2 of [TS 38.213], except that N should be used TA = 0 on the PUSCH msgA transmission;

[0109] - given by clause 4.2 of [TS 38.213] is derived from the higher layer parameters ta-Common, ta-CommonDrift and ta-CommonDriftVariant (if configured), otherwise

[0110] - given by clause 4.2 of [TS 38.213] is calculated by the UE based on the UE position and service-satellite-ephemeris related higher layer parameters (if configured), otherwise

[0111] Figure 7 It is in 3GPP TS 38.211V17.5.0 Figure 4 .3.1-1: Re-enactment of uplink-downlink timing association.

[0112] *************************END OF QUOTE********************

[0113] The maintenance of UL time alignment and TA reporting in NTN is specified in TS 38.321 ([3] 3GPP TS 38.321 V17.5.0) as follows:

[0114] *************************Quote starts [3]************************

[0115] 5.2 Maintenance of uplink time alignment

[0116] RRC configures the following parameters to maintain UL time alignment:

[0117] -timeAlignmentTimer (per TAG), which controls the time the MAC entity considers that the serving cells belonging to the associated TAG need to be aligned for uplink time;

[0118] …

[0119] The MAC entity shall:

[0120] 1> When receiving the opportunity advance command MAC CE, and if the indicated TAG has been used to maintain N TA (as defined in TS 38.211[2]), then:

[0121] 2> Apply timing advance command for the indicated TAG;

[0122] …

[0123] 3> Start or restart the timeAlignmentTimer associated with the indicated TAG.

[0124] 1> When a timing advance command is received in a random access response message for a serving cell belonging to a TAG or in a MSGB for a SpCell:

[0125] 2> If the MAC entity does not select a random access preamble among the contention-based random access preambles:

[0126] 3> Apply the timing advance command for this TAG;

[0127] 3> Start or restart the timeAlignmentTimer associated with this TAG.

[0128] 2> Otherwise, if the timeAlignmentTimer associated with this TAG is not running:

[0129] 3> Apply the timing advance command for this TAG;

[0130] 3>Start the timeAlignmentTimer associated with this TAG;

[0131] 3> when contention resolution as described in Section 5.1.5 is deemed unsuccessful; or

[0132] 3> When contention resolution is considered successful for the SI request as described in clause 5.1.5 after transmitting the HARQ feedback containing the UE contention resolution indicator MAC CE for the MAC PDU:

[0133] 4> Stop the timeAlignmentTimer associated with this TAG.

[0134] …

[0135] 2> Otherwise:

[0136] 3> Ignore the received timing advance command.

[0137] 1> When an Absolute Timing Advance Command is received in response to an MSGA transmission containing a C-RNTI MAC CE as specified in clause 5.1.4a:

[0138] 2> Advance command for PTAG application timing;

[0139] 2> If there is an ongoing positioning SNR transmission in RRC_INACTIVE as described in clause 5.26:

[0140] 3> Start or restart the inactivePosSRS-TimeAlignmentTimer associated with the indicated TAG.

[0141] …

[0142] 3> Start or restart the timeAlignmentTimer associated with PTAG.

[0143] …

[0144] 1> When an instruction has been received from an upper layer to start a TimeAlignmentTimer associated with a PTAG:

[0145] 2>Start the TimeAlignmentTimer associated with PTAG.

[0146] 1>When timeAlignmentTimer expires:

[0147] 2> If timeAlignmentTimer is associated with PTAG:

[0148] 3> Clear all HARQ buffers for all serving cells;

[0149] 3> Notify RRC to release PUCCH for all serving cells (if configured);

[0150] 3> Notify RRC to release SRS for all serving cells (if configured);

[0151] 3> Clear any configured downlink assignments and configured uplink grants;

[0152] 3> Clear any PUSCH resources used for semi-persistent CSI reporting;

[0153] 3> All running timeAlignmentTimers are considered to have expired;

[0154] 3> Maintain N of all tags TA (Defined in TS 38.211[2]).

[0155] 2> Otherwise, if timeAlignmentTimer is associated with a STAG, for all serving cells belonging to this TAG:

[0156] 3> Clear all HARQ buffers;

[0157] 3> Notify RRC to release PUCCH (if configured);

[0158] 3> Notify RRC to release SRS (if configured);

[0159] 3> Clear any configured downlink assignments and configured uplink grants;

[0160] 3> Clear any PUSCH resources used for semi-persistent CSI reporting;

[0161] 3> Maintain the N of this TAG TA (defined in TS 38.211[2]).

[0162] …

[0163] When the MAC entity stops uplink transmission due to the fact that the maximum uplink transmission timing difference between the TAGs of the MAC entity or the maximum uplink transmission timing difference between the TAGs of any MAC entity of the UE is exceeded, the MAC entity considers that the timeAlignmentTimer associated with the SCell has expired.

[0164] When the timeAlignmentTimer associated with the TAG to which the serving cell belongs is not running, the CG-SDT procedure is not in progress, and the SRS transmission in RRC_INACTIVE as in clause 5.26 is not in progress, the MAC entity shall not perform any uplink transmission on this serving cell except for the random access preamble and MSGA transmission. In addition, when the timeAlignmentTimer associated with the PTAG is not running, the CG-SDT procedure is not in progress, and the SRS transmission in RRC_INACTIVE as in clause 5.26 is not in progress, the MAC entity shall not perform any uplink transmission on any serving cell except for the random access preamble and MSGA transmission on the SpCell. When the cg-SDT-TimeAlignmentTimer is not running and the inactivePosSRS-TimeAlignmentTimer is not running during the ongoing CG-SDT procedure triggered as in clause 5.27, the MAC entity shall not perform any uplink transmission except for the random access preamble and MSGA transmission.

[0165] ********************Next quote****************************

[0166] 5.4.8 Timing of early reporting

[0167] The Timing Advance Reporting procedure is used in non-terrestrial networks to provide the gNB with an estimate of the UE’s Timing Advance value (i.e., T as defined in the UE’s TA formula). TA , see clause 4.3.1 of TS 38.211[2].

[0168] RRC controls the timing advance reporting by configuring the following parameters:

[0169] -offsetThresholdTA;

[0170] -timingAdvanceSR.

[0171] If any of the following events occurs, a Timing Advance report (TAR) shall be triggered:

[0172] -After an indication from an upper layer to trigger an early reporting of the opportunity;

[0173] -After offsetThresholdTA is configured by upper layers, if the UE has not previously reported the timing advance value to the current serving cell;

[0174] - If the change between the current estimate of the Timing Advance value and the last reported Timing Advance value is equal to or greater than offsetThresholdTA (if configured).

[0175] The MAC entity shall:

[0176] 1> If the timing advance reporting procedure determines that at least one TAR has been triggered and not cancelled, then:

[0177] 2> If, due to logical channel prioritization, UL-SCH resources are available for new transmissions and the UL-SCH resources can accommodate the Opportunity Advance Report MAC CE plus its subheader, then:

[0178] 3> Instruct the multiplexer and assembler to generate the opportunity to report the MAC CE in advance, as defined in clause 6.1.3.56.

[0179] 2> Otherwise

[0180] 3> If timingAdvanceSR is configured with the value enabled:

[0181] 4>Trigger scheduling request.

[0182] NOTE: UL-SCH resources are considered available if the MAC entity has been configured with, received or determined an uplink grant. If the MAC entity has determined that UL-SCH resources are available at a given point in time, this does not necessarily imply that the UL-SCH resources are available for use at that point in time.

[0183] Even when multiple events have triggered timing advance reporting, a MAC PDU shall contain at most one timing advance reporting MAC CE.The timing advance reporting MAC CE shall be generated based on the latest available estimate of the UE's timing advance value before the MAC PDU is compiled.

[0184] When a MAC PDU is transmitted and this PDU contains an Opportunity Advance Report MAC CE, all triggered Opportunity Advance Reports shall be cancelled.

[0185] ********************Next quote****************************

[0186] 6.1.3.4 Timing Advance Command MAC CE

[0187] The Opportunity Advance Command MAC CE is identified by a MAC subheader with an LCID as specified in Table 6.2.1-1.

[0188] It has a fixed size and consists of a single octet as defined below ( Figure 6 .1.3.4-1):

[0189] -TAG Identity (TAG ID): This field indicates the TAG identity of the addressed TAG. The TAG containing the SpCell has a TAG identity of 0. The length of the field is 2 bits;

[0190] -Timing Advance Command: This field indicates the index value T used to control the amount of timing adjustment that the MAC entity (as specified in TS 38.213) must apply. A (0, 1, 2, ..., 63). The length of the field is 6 bits.

[0191] Figure 8 It is in 3GPP TS 38.321V17.5.0 Figure 6 .1.3.4-1: Reappearance of timing advance command MAC CE.

[0192] ********************Next quote****************************

[0193] 6.1.3.56 Timing of Early Reporting of MAC CE

[0194] The Opportunity Advance Report MAC CE is identified by a MAC subheader with an LCID as specified in Table 6.2.1-2. It has a fixed size and consists of two octets defined as follows ( Figure 6 .1.3.56-1):

[0195] -R: reserved bit, set to 0;

[0196] - Timing Advance: In FR1, the Timing Advance field indicates the smallest integer number of slots greater than or equal to the Timing Advance value using a subcarrier spacing of 15 kHz (see clause 4.3.1 of TS 38.211 [2]). The length of the field is 14 bits.

[0197] Fig. 9 It is in 3GPP TS 38.321V17.5.0 Figure 6 .1.3.56-1: Reappearance of the timing advance reporting MAC CE.

[0198] *************************END OF QUOTE********************

[0199] The RRC connection / reconfiguration procedure and TA reporting procedure in the upper layer (ie, RRC) are specified in TS 38.331 ([4] 3GPP TS 38.331 V17.5.0) as follows:

[0200] *************************Quote starts [4]************************

[0201] 5.3.3RRC Connection Establishment

[0202] 5.3.3.1 Overview

[0203] Fig.10 It is in 3GPP TS 38.331V17.5.0 Figure 5 .3.3.1-1: Reproduction of RRC connection establishment (success).

[0204] …

[0205] The purpose of this procedure is to establish an RRC connection. The RRC connection establishment involves SRB1 establishment. The procedure is also used to transfer initial NAS dedicated information / messages from the UE to the network.

[0206] The network applies the program as follows:

[0207] -When an RRC connection is established;

[0208] - When the UE is resuming or re-establishing an RRC connection and the network is unable to retrieve or verify the UE context. In this case, the UE receives RRCSetup and responds with RRCSetupComplete.

[0209] …

[0210] 5.3.3.2 Initiation

[0211] The UE initiates the procedure when upper layers request establishment of an RRC connection while the UE is in RRC_IDLE and it has acquired basic system information, or for sidelink communication as specified in clause 5.3.3.1a.

[0212] Before initiating this procedure, the UE shall ensure that it has valid and up-to-date basic system information as specified in clause 5.2.2.2.

[0213] Immediately after initiating the procedure, the UE shall:

[0214] …

[0215] 2> Apply the preset MAC cell group configuration as specified in 9.2.2;

[0216] 2> Apply CCCH configuration as specified in 9.1.1.2;

[0217] 2> Apply timeAlignmentTimerCommon contained in SIB1;

[0218] 1>Start timer T300;

[0219] 1> Initiate the transmission of RRCSetupRequest message according to 5.3.3.3;

[0220] 5.3.3.3 Actions related to the transmission of the RRCSetupRequest message

[0221] The UE shall set the content of the RRCSetupRequest message as follows:

[0222] …

[0223] 1> If ta-Report is configured with the value enabled and the UE supports TA reporting:

[0224] 2> Instruct the lower layer to initiate the TA report;

[0225] The UE shall submit an RRCSetupRequest message to lower layers for transmission.

[0226] *************************Next Quote********************

[0227] 5.3.5RRC Reconfiguration

[0228] 5.3.5.1 Overview

[0229] Fig.11 It is in 3GPP TS 38.331V17.5.0 Figure 5 .3.5.1-1: Reproduction of RRC reconfiguration (successful).

[0230] Fig.12 It is in 3GPP TS 38.331V17.5.0 Figure 5 .3.5.1-2: Recurrence of RRC reconfiguration (failure).

[0231] The purpose of this procedure is to modify the RRC connection, such as establish / modify / release RB / BH RLC channel / Uu relay RLC channel / PC5 ​​relay RLC channel, perform reconfiguration with synchronization, set / modify / release measurements, add / modify / release SCell and cell group, add / modify / release conditional handover configuration, add / modify / release conditional PSCell change or conditional PSCell add configuration. As part of the procedure, NAS specific information may be transferred from the network to the UE.

[0232] …

[0233] 5.3.5.2 Initiation

[0234] The network may initiate the RRC reconfiguration procedure to the UE in RRC_CONNECTED. The network applies the procedure as follows:

[0235] - Establishment of RBs is performed only when AS security has been activated (not SRB1, which is established during RRC connection establishment);

[0236] …

[0237] - reconfigurationWithSync is included in the masterCellGroup only if AS security has been activated, and SRB2 with at least one DRB or multicast MRB or SRB2 for IAB is set and not suspended;

[0238] -ConditionalReconfiguration for CPC is included only if at least one RLC bearer is set up in the SCG;

[0239] - ConditionalReconfiguration for CHO or CPA is included only if AS security has been activated, and SRB2 with at least one DRB or multicast MRB or SRB2 for IAB is set and not suspended.

[0240] 5.3.5.3 UE receives RRCReconfiguration

[0241] Upon receiving RRCReconfiguration or performing a conditional reconfiguration (CHO, CPA or CPC), the UE shall perform the following actions:

[0242] …

[0243] 1> If RRCReconfiguration contains masterCellGroup:

[0244] 2>According to 5.3.5.5, perform cell group configuration for the received masterCellGroup;

[0245] …

[0246] 1> If the RRCReconfiguration message contains conditionalReconfiguration:

[0247] 2> Perform conditional reconfiguration as specified in 5.3.5.13;

[0248] …

[0249] 1> Otherwise (RRCReconfiguration received via SRB1):

[0250] …

[0251] 2> If reconfigurationWithSync is included in spCellConfig of MCG:

[0252] 3> If ta-Report is configured with the value enabled and the UE supports TA reporting:

[0253] 4> Instruct the lower layer to initiate the TA report;

[0254] 2> Submit an RRCReconfigurationComplete message to the lower layer via SRB1 for transmission using the new configuration;

[0255] ********************Next quote****************************

[0256] 5.3.7RRC Connection Reestablishment

[0257] 5.3.7.1 Overview

[0258] Fig.13 It is in 3GPP TS 38.331V17.5.0 Figure 5 .3.7.1-1: Re-establishment of RRC connection (success).

[0259] Fig.14 It is in 3GPP TS 38.331V17.5.0 Figure 5 .3.7.1-2: RRC re-establishment falls back to re-establishment of RRC establishment (success).

[0260] The purpose of this procedure is to re-establish the RRC connection. A UE in RRC_CONNECTED for which AS security has been activated in case of SRB2 and at least one DRB / Multicast MRB setup or for which the IAB is SRB2 may initiate the procedure in order to continue the RRC connection. The connection re-establishment is successful if the network is able to find and verify a valid UE context, or if the UE context cannot be retrieved and the network responds with RRCSetup according to clause 5.3.3.4.

[0261] …

[0262] 5.3.7.2 Initiation

[0263] The UE initiates the procedure when one of the following conditions is met:

[0264] 1> According to 5.3.10, after detecting radio link failure of the MCG and t316 is not configured; or

[0265] 1> According to 5.3.10, when SCG transmission is suspended after detecting radio link failure of MCG; or

[0266] 1> According to 5.3.10, after detecting a radio link failure to the MCG when a PSCell change or PSCell addition is in progress; or

[0267] 1> According to 5.3.10, when the SCG is deactivated after detecting a radio link failure with the MCG; or

[0268] 1> after a synchronous reconfiguration of the MCG fails according to clause 5.3.5.8.3; or

[0269] 1> after movement due to NR failure in accordance with clause 5.4.3.5; or

[0270] 1> after an integrity check failure indication from lower layers on SRB1 or SRB2, unless an integrity check failure is detected on the RRCReestablishment message; or

[0271] 1> after an RRC connection reconfiguration fails in accordance with clause 5.3.5.8.2; or

[0272] …

[0273] Immediately after initiating the procedure, the UE shall:

[0274] …

[0275] 1> If the UE is not configured with attemptCondReconfig:

[0276] 2>Reset MAC;

[0277] 2>Release spCellConfig (if configured);

[0278] 2> Suspend all RBs and BH RLC channels for IAB-MT and Uu relay RLC channels for L2 U2N relay UEs, except SRB0 and broadcast MRB;

[0279] 2> Release MCG SCell (if configured);

[0280] …

[0281] 3> Cell selection is performed according to the cell selection procedure as specified in TS 38.304.

[0282] …

[0283] 5.3.7.3 Actions after cell selection when T311 is in operation

[0284] After selecting a suitable NR cell, the UE shall:

[0285] …

[0286] 2> Apply the preset MAC cell group configuration as specified in 9.2.2;

[0287] …

[0288] 2> Apply timeAlignmentTimerCommon contained in SIB1;

[0289] 2> Initiate the transmission of RRCReestablishmentRequest message according to 5.3.7.4;

[0290] …

[0291] 5.3.7.4 Actions related to the transmission of the RRCReestablishmentRequest message

[0292] The UE shall set the content of the RRCReestablishmentRequest message as follows:

[0293] …

[0294] 1> If ta-Report is configured with the value enabled and the UE supports TA reporting:

[0295] 2> Instruct the lower layer to initiate the TA report;

[0296] 1> Submit the RRCReestablishmentRequest message to the lower layer for transmission.

[0297] *************************Next Quote********************

[0298] 5.3.12 UE actions immediately following a PUCCH / SRS release request

[0299] Upon receiving a PUCCH release request from lower layers, the UE shall, for all bandwidth parts of the indicated serving cell:

[0300] 1> Release the PUCCH-CSI-Resource configured in CSI-ReportConfig;

[0301] 1> Release the SchedulingRequestResourceConfig instance configured in PUCCH-Config.

[0302] Upon receiving the SRS release request from lower layers, for all bandwidth parts of the indicated serving cell, the UE shall:

[0303] 1> Release the SRS-Resource instance configured in SRS-Config.

[0304] Upon receiving the positioning CRS configuration for the RRC_INACTIVE release request from lower layers, the UE shall:

[0305] 1> Release the configured srs-PosRRC-Inactive.

[0306] *************************Next Quote********************

[0307] 5.3.13RRC Connection Recovery

[0308] 5.3.13.1 Overview

[0309] Fig.15 It is in 3GPP TS 38.331V17.5.0 Figure 5 .3.13.1-1: Reproduction of RRC connection recovery (success).

[0310] Fig.16 It is in 3GPP TS 38.331V17.5.0 Figure 5 .3.13.1-2: RRC connection recovery falls back to the reappearance of RRC connection establishment (success).

[0311] …

[0312] The purpose of this procedure is to resume a suspended RRC connection, including resuming SRB, DRB and multicast MRB, or performing RNA update. This procedure is also used to initiate SDT in RRC_INACTIVE.

[0313] …

[0314] 5.3.13.2 Initiation

[0315] The UE initiates the procedure when upper layers or the AS (when responding to RAN paging, after triggering RNA update when the UE is in RRC_INACTIVE, for NR sidelink communication / discovery / V2X sidelink communication as specified in clause 5.3.13.1a) requests resumption of a suspended RRC connection or requests initiation of resumption for SDT as specified in clause 5.3.13.1b.

[0316] Before initiating this procedure, the UE shall ensure that it has valid and up-to-date basic system information as specified in clause 5.2.2.2.

[0317] Immediately after initiating the procedure, the UE shall:

[0318] …

[0319] 2> Apply the preset MAC cell group configuration as specified in 9.2.2;

[0320] …

[0321] 2> Apply timeAlignmentTimerCommon contained in SIB1;

[0322] …

[0323] 1> If ta-Report is configured with the value enabled and the UE supports TA reporting:

[0324] 2> Instruct the lower layer to initiate the TA report;

[0325] …

[0326] 1> Initiate the transmission of RRCResumeRequest message or RRCResumeRequest1 according to 5.3.13.3.

[0327] *************************END OF QUOTE********************

[0328] Some configurations related to NTN and TAR may be provided by the NW as specified in TS 38.331 ([4] 3GPP TS 38.331 V17.5.0):

[0329] ******************** Quote starts [4]************************

[0330] -RRCReconfiguration

[0331] The RRCReconfiguration message is a command to modify the RRC connection. It can convey information for measurement configuration, mobility control, radio resource configuration (including RB, MAC main configuration and physical channel configuration) and AS security configuration.

[0332]

[0333]

[0334]

[0335] *************************Next Quote********************

[0336] -RRCResumeRRCResume message is used to resume a suspended RRC connection.

[0337]

[0338]

[0339] *************************Next quote*************************-RRCSetupRRCSetup message is used to establish SRB1.

[0340]

[0341]

[0342] ********************Next Quote****************************-SIB19

[0343] SIB19 contains satellite assistance information for NTN access.

[0344] SIB19 Information Elements

[0345]

[0346]

[0347]

[0348]

[0349] ********************Next quote****************************

[0350] -CellGroupConfig

[0351] The CellGroupConfig IE is used to configure a master cell group (MCG) or a secondary cell group (SCG). A cell group includes a MAC entity, a logical channel set with an associated RLC entity, a primary cell (SpCell), and one or more secondary cells (SCells).

[0352] CellGroupConfig Information Element

[0353] --Configuration of a cell group:

[0354]

[0355]

[0356]

[0357]

[0358] *************************Next Quote********************

[0359] -MAC-CellGroupConfigIEMAC-CellGroupConfig is used to configure the MAC parameters of the cell group, including DRX. MAC-CellGroupConfig information element

[0360]

[0361]

[0362]

[0363] ********************Next Quote****************************-NTN-ConfigIENTN-Config provides the parameters required by the UE to access NR via NTN access. NTN-Config information element

[0364]

[0365]

[0366]

[0367]

[0368]

[0369]

[0370] ********************Next quote****************************

[0371] -ServingCellConfigCommon

[0372] The IE ServingCellConfigCommon is used to configure the cell specific parameters of the serving cell of the UE. The IE contains parameters that the UE will usually obtain from the SSB, MIB or SIB when accessing the cell from IDLE. Through this IE, the network provides this information in dedicated signaling when configuring an SCell or additional cell group (SCG) for the UE. The network also provides this information for SpCells (MCG and SCG) immediately after reconfiguration with synchronization.

[0373] ServingCellConfigCommon Information Elements

[0374]

[0375] ********************Next quote****************************

[0376] -TAR-Config

[0377] IE TAR-Config is used to configure Opportunity Advance Reporting in non-terrestrial networks.

[0378] TAR-Config Information Elements

[0379]

[0380]

[0381]

[0382] *************************END OF QUOTE********************

[0383] The validity timer (or UL synchronization timer) (e.g., T430) processing is specified in TS 38.331 ([4] 3GPP TS 38.331 V17.5.0 and [9] 3GPP TS 38.331 V17.6.0) and TS 38.321 ([3] 3GPP TS 38.321 V17.5.0) as follows:

[0384] *************************Quote starts [4]*************************

[0385] 5.2.2.4.21 Actions to be performed immediately after receiving SIB19

[0386] After receiving SIB19, the UE in RRC_CONNECTED shall:

[0387] 1> Start or restart T430 of the serving cell, where the timer value is set to the ntn-UlSyncValidityDuration of the serving cell starting from the subframe indicated by the epochTime of the free serving cell;

[0388] NOTE: The UE shall attempt to reacquire SIB19 by UE implementation before the end of the duration indicated by ntn-UlSyncValidityDuration and epochTime.

[0389] ********************Next quote****************************

[0390] 5.2.2.6 T430 Expiration

[0391] The UE shall:

[0392] 1> If T430 of the serving cell expires and if it is in RRC_CONNECTED:

[0393] 2> Notify the lower layer that UL synchronization has been lost;

[0394] 2> Get SIB19 as defined in clause 5.2.2.3.2;

[0395] 2> After successfully obtaining SIB19:

[0396] 3>Notify the lower layer when UL synchronization is achieved;

[0397] NOTE: The exact time to obtain UL synchronization (after acquiring SIB19) depends on the UE implementation, which may be from the subframe indicated by epochTime, and optionally before the subframe indicated by epochTime.

[0398] *************************END OF QUOTE********************

[0399] *************************Quote starts [9]*************************

[0400] 5.3.5.5 Cell Group Configuration

[0401] 5.3.5.5.1 Overview

[0402] …

[0403] The UE performs the following actions based on the received CellGroupConfig IE:

[0404] 1> If CellGroupConfig contains spCellConfig with reconfigurationWithSync:

[0405] 2>Perform reconfiguration with synchronization according to 5.3.5.5.2;

[0406] …

[0407] 5.3.5.5.2 Reconfiguration with Synchronization

[0408] The UE shall carry out the following actions to perform reconfiguration with synchronization.

[0409] 1> If AS security is not activated, the actions are taken immediately after going to RRC_IDLE as specified in 5.3.11, and the release reason is 'other', after which the procedure ends;

[0410] 1> Stop timer T430 (if it is running);

[0411] …

[0412] 2> If this procedure is performed for an MCG, or if this procedure is performed for an SCG that is not indicated as deactivated in the E-UTRA or NR RRC message in which the RRCReconfiguration message is embedded, then:

[0413] 3>Start timer T304 for the corresponding SpCell, where the timer value is set to t304, as included in reconfigurationWithSync;

[0414] …

[0415] 2> Start DL synchronization with the target SpCell;

[0416] 2> Apply the specified BCCH configuration defined in 9.1.1.1 to the target SpCell;

[0417] 2> Get the MIB of the target SpCell, which is scheduled as specified in TS 38.213;

[0418] 2> If NTN-Config is configured for the target cell:

[0419] 3> According to the target cell NTN-Config, start timer T430, where the timer value is set to ntn-UlSyncValidityDuration from the subframe indicated by the free epochTime;

[0420] …

[0421] 3> Reset the MAC entity of this cell group;

[0422] 3> The SCells of this cell group that are not included in the SCellToAddModList in the RRCReconfiguration message (if configured) are considered to be in a deactivated state;

[0423] 3> Apply the value of newUE-Identity as the C-RNTI for this cell group;

[0424] 3>Configure the lower layer according to the received spCellConfigCommon;

[0425] 3> If the received reconfigurationWithSync contains any additional fields not previously covered, configure the lower layer according to the additional fields.

[0426] ********************Next quote****************************

[0427] 5.3.5.13 Conditional Reconfiguration

[0428] 5.3.5.13.1 Overview

[0429] The network configures one or more candidate target SpCells for the UE in a conditional reconfiguration. The UE evaluates the conditions of each configured candidate target SpCell. The UE applies the conditional reconfiguration associated with one of the target SpCells that satisfies the associated execution condition. The network provides configuration parameters for the target SpCell in the ConditionalReconfiguration IE.

[0430] …

[0431] 5.3.5.13.4 Conditional Reconfiguration Evaluation

[0432] The UE shall:

[0433] 1>For each condReconfigId inside VarConditionalReconfig:

[0434] 2> If RRCReconfiguration in condRRCReconfig includes a masterCellGroup containing reconfigurationWithSync:

[0435] 3> Treat cells with physical cell identities matching the value indicated in ServingCellConfigCommon contained in reconfigurationWithSync within masterCellGroup in the received condRRCReconfig as applicable cells;

[0436] …

[0437] 2> For each measId contained in the measIdList within the VarMeasConfig indicated in the condExecutionCond or condExecutionCondSCG associated with condReconfigId:

[0438] 3> if condEventId is associated with condEventT1, and if the entry conditions applicable to this event associated with condReconfigId (i.e., the event corresponding to the condEventId of the corresponding condTriggerConfig within VarConditionalReconfig) have been met for the applicable cell; or

[0439] 3> if condEventId is associated with condEventD1, and if the entry conditions applicable to this event associated with condReconfigId (i.e., the event corresponding to the condEventId of the corresponding condTriggerConfig in VarConditionalReconfig) have been met for the applicable cells during the corresponding timeToTrigger defined for this event in VarConditionalReconfig; or

[0440] 3> If condEventId is associated with condEventA3, condEventA4, or condEventA5, and if the entry conditions applicable to this event associated with condReconfigId (i.e., the event corresponding to the condEventId of the corresponding condTriggerConfig in VarConditionalReconfig) have been met for the applicable cells for all measurements after layer 3 filtering performed during the corresponding timeToTrigger defined for this event in VarConditionalReconfig:

[0441] 4> It is considered that the event associated with the measId has been satisfied;

[0442] 3> If the measId of this event associated with condReconfigId has been modified; or

[0443] 3> if condEventId is associated with condEventT1, and if the leaving condition applicable to this event associated with condReconfigId (i.e., the event corresponding to the condEventId of the corresponding condTriggerConfig within VarConditionalReconfig) has been met for the applicable cell; or

[0444] 3> if condEventId is associated with condEventD1, and if the leaving condition applicable to this event associated with condReconfigId (i.e., the event corresponding to the condEventId of the corresponding condTriggerConfig in VarConditionalReconfig) has been satisfied for the applicable cell during the corresponding timeToTrigger defined for this event in VarConditionalReconfig; or

[0445] 3> If condEventId is associated with condEventA3, condEventA4, or condEventA5, and if the leaving condition applicable to this event associated with condReconfigId (i.e., the event corresponding to the condEventId of the corresponding condTriggerConfig in VarConditionalReconfig) has been met for the applicable cells for all measurements after layer 3 filtering performed during the corresponding timeToTrigger defined for this event in VarConditionalReconfig:

[0446] 4> It is considered that the event associated with the measId is not satisfied;

[0447] 2> If the events associated with all measIds in the condTriggerConfig of the applicable cell have been satisfied:

[0448] 3> The applicable cell associated with the condReconfigId is regarded as the triggered cell;

[0449] 3> Initiate conditional reconfiguration execution as specified in 5.3.5.13.5;

[0450] …

[0451] 5.3.5.13.5 Conditional Reconfiguration Execution

[0452] The UE shall:

[0453] 1>For the selected cell where conditional reconfiguration is performed:

[0454] 2> Apply the stored condRRCReconfig of the selected cell and perform the actions specified in 5.3.5.3;

[0455] *************************END OF QUOTE********************

[0456] *************************Quote starts [3]************************

[0457] 5.2a Maintenance of UL synchronization

[0458] For each serving cell, the MAC entity shall:

[0459] 1> If an indication of uplink synchronization has been received from upper layers (see clause 5.2.2.6 of TS 38.331 [4]):

[0460] 2> Allow uplink transmission on the serving cell.

[0461] 1> If an indication of uplink synchronization loss is received from upper layers (see clause 5.2.2.6 of TS 38.331 [4]):

[0462] 2> Clear all HARQ buffers;

[0463] 2> Do not perform any uplink transmission on the serving cell.

[0464] NOTE: The MAC entity suspends all UL operations (e.g., stops RACH, SR, and UL HARQ operations) after receiving an indication of uplink synchronization loss, and resumes operations upon receiving an indication of uplink synchronization.

[0465] *************************END OF QUOTE********************

[0466] Furthermore, at the RAN2 meeting the following agreement was reached for an unchanged PCI mechanism (and / or satellite handover (with resynchronization)).

[0467] At RAN2#121bis meeting:

[0468] - In case of quasi-geo fixed cells, for hard satellite handover within the same SSB frequency and same gNB (no key change), satellite handover without change of PCI (no L3 mobility required) is supported unless RAN1 identifies major technical issues (as usual, RAN2 will work on minimizing the specification impact to make it suitable for Rel-18).

[0469] At RAN2#122 meeting:

[0470] - In hard handover unchanged PCI scenario (i.e. no handover), the UE needs to know when the UE attempts to resynchronize. (FFS if a new "t-Start" / t-gap is needed, or if the t-Service can be reused (i.e. no other IE) if the gap is very short / zero).

[0471] At RAN2#123 meeting:

[0472] - An explicit indication will be introduced to enable invariant PCI switching;

[0473] - The unchanged PCI mechanism can be applied to the case where the coverage gap is zero or negligible (where t-gap or t-start does not need to be introduced). FFS is performed on whether to support scenarios where t-gap or t-start needs to be introduced;

[0474] - PCI unchanged procedure can be implemented without implementing RACH;

[0475] - In the case of unchanged PCI, the UE considers that the UL synchronization timer expires at t-Service (current cell stop time) to stop any UL operation. FFS is performed on timeAlignmentTimer processing;

[0476] - In case of unchanged PCI, for RACH based solution, the UE can trigger RACH immediately after DL synchronization with the new satellite.

[0477] At the RAN2#123bis meeting:

[0478] - When defining the Rel-18 unchanged PCI solution, we did not consider the impact on Rel-17 UE behavior (or Rel-18 UEs that do not support unchanged PCI).

[0479] - The network provides the UE with the synchronization information of the target satellite in advance via broadcast transmission before satellite switching.

[0480] -RAN2 confirms that satellite handover without PCI change is applicable only to quasi-geo-fixed systems.

[0481] - Only 1 target satellite information (ie, NTN-config) of the serving cell is provided in SIB19. FFS is performed on accurate transmission.

[0482] -The SMTC configuration of the target satellite requires further discussion:

[0483] ■ Regarding whether and how to provide the SMTC configuration of the target satellite for FFS.

[0484] ■About how to handle SMTC adjustments for FFS.

[0485] -Supports soft satellite handover in Rel-18.

[0486] - There will be an indication whether hard or soft handover is used (FFS is done explicitly or implicitly).

[0487] - At least for soft satellite handover, the network provides the UE with the SSB information of the target satellite. FFS for details: options include, for example, indicating the time offset / information or indicating a different SSB index of the target satellite (FFS for hard satellite handover)

[0488] - In soft satellite handover, the UE can start synchronization with the target satellite before the T-service of the source satellite.

[0489] - Introduced T-start, which indicates the earliest time when the UE can start synchronization with the target satellite (actual transmission is FFS). In a soft handover scenario, the T-start of the target satellite is earlier than the T-service of the source satellite (FFS is performed whether T-start is also used for hard satellite handover).

[0490] - For soft satellite handover, the exact time when the UE starts synchronization with the target satellite (between T-start and T-service) depends on the UE implementation.

[0491] - When the UE switches to the target satellite, the UE is not required to be connected to the source satellite.

[0492] Following the NR RRC specification TS 38.331 ([4] 3GPP TS 38.331 V17.5.0), the relevant text for satellite handover in CR running NTN Rel-18 ([5] R2-230934) is quoted as follows:

[0493] *********************Quote begins [5]****************************

[0494] SIB19 Information Elements

[0495]

[0496]

[0497]

[0498] *************************END OF QUOTE********************

[0499] The non-terrestrial network (NTN) can be regarded as a next-generation radio access network (NG-RAN) composed of a next-generation Node B (gNB), which provides non-terrestrial new air interface (NR) access to user equipment (UE) with the help of NTN payloads and NTN gateways carried on NTN vehicles in the air or space. UE can be linked to, reside on and / or connected to the NTN network involving air / space transmission. NTN can include various platforms, including Low Earth Orbit (LEO) satellites, Medium Earth Orbit (MEO) satellites, Highly Elliptical Orbit (HEO) satellites, Geostationary Earth Orbit (GEO) satellites, Geostationary Synchronous Orbit (GSO) satellites, Non-Geostationary Synchronous Orbit (NGSO) satellites, and / or High Altitude Platform Station (HAPS). LEO satellites may have earth-fixed beams (e.g., beams temporarily fixed at one location during a period of time) or earth-moving beams (e.g., beams continuously moving with the satellite). NTNs can provide wide area coverage in scenarios where terrestrial networks (TNs) are not feasible (e.g., deserts, polar regions, and / or on airplanes), and provide network (NW) access.

[0500] The NW may provide NTN information to the UE. The NTN information may be a parameter required for the UE to access the NW via NTN access. The NTN information may be or include at least one or more NTN configurations (e.g., NTN-Config), time information (e.g., t-Service), a reference location (e.g., referenceLocation), and a distance threshold (e.g., distanceThresh). The NTN information and / or the NTN configuration (e.g., NTN-Config) may be or include satellite assistance information. The NW may provide the NTN information to the UE in NTN-specific system information (e.g., SIB19) or a radio resource control (RRC) message (e.g., RRCReconfiguration), for example, via a serving cell. The NTN-specific system information may be a system information block (SIB) including NTN information. The NTN configuration (e.g., NTN-Config) may be or (at least) include an epoch time (e.g., epochTime), a validity duration (e.g., ntn-UlSyncValidityDuration), a satellite ephemeris (e.g., ephemerisInfo), and / or a common timing advance (TA) (e.g., ta-Info). The validity duration (e.g., ntn-UlSyncValidityDuration) may indicate a maximum time that the UE may apply satellite information and / or NTN-specific system information without acquiring new satellite information and / or NTN-specific system information (e.g., SIB19). The validity duration (e.g., ntn-UlSyncValidityDuration) and / or the epoch time (e.g., epochTime) may be associated with (or applied to) NTN-specific system information (e.g., SIB19), NTN configuration (e.g., NTN-Config), satellite information, satellite ephemeris (e.g., ephemerisInfo), and / or common TA (e.g., ta-Info). The time information (e.g., t-Service) may be a time when the serving cell stops serving. The time information (e.g., t-Service) may be a timing when the UE will leave the coverage of the serving cell. The time information (e.g., t-Service) may indicate time information about when the serving cell will stop providing service to the area currently covered by it.

[0501] Throughout this disclosure, SIB19 may be system information for a serving cell. SIB19 may be system information specific to NTN. SIB19 may contain satellite assistance information. SIB19 may contain uplink (UL) synchronization information for NTN. System information may be referred to as a system information block. Throughout this disclosure, one, some and / or all instances of "NTN configuration" may correspond to, may be supplemented by and / or may be replaced by "NTN information", "satellite information", "NTN-Config" and / or "assistance information".

[0502] The UE shall maintain UL time alignment with the serving cell. The UE shall maintain the TA value for UL / downlink (DL) transmissions. The (full) TA value is the T as specified in TS 38.211 ([2] 3GPP TS 38.211 V17.5.0). TA . T TA Based on NW configuration and / or Composition. TA，offset Configured by NW, for example via n-TimingAdvanceOffset or a preset value. TA Indicated or adjusted by TA command. In TN, UE uses N TA and N TA，offset Calculate T TA , and you can not use and The UE will receive N via a Random Access (RA) response (e.g., Random Access Response (RAR), MSGB) during the RA procedure. TA The UE shall receive N from the Opportunity Advance Command Media Access Control (MAC) Control Element (CE) in RRC Connected Mode. TA For a handover without a random access channel (RACH), the N may be indicated to the UE via an RRC reconfiguration message (eg, RRCConnectionReconfiguration). TAZero or the same as the Primary Timing Advance Group (PTAG). A set of service cells with the same TA will be grouped in a Timing Advance Group (TAG). A TAG including a special cell (SpCell) is a PTAG. A TAG excluding SpCell is a secondary TAG (STAG). The UE can have one PTAG and up to three STAGs in each cell group. SpCell is used as the timing reference for PTAG. The activated secondary cell (SCell) of STAG is used as the timing reference for STAG. And, the UE maintains a TA timer (e.g., timeAlignmentTimer) for each TAG.

[0503] In NTN, the UE will pre-compensate the TA value based on satellite assistance information (e.g., parameters in NTN-Config) and / or the UE's location. TA and N TA，offset In addition, UE targets T TA Also calculate / derive and is derived from the common TA information of the satellites. And, It is pre-compensated by the UE using the UE position and satellite positions based on the ephemeris information. is a common TA value and / or a satellite-specific TA value. is a UE-specific TA value. The UE will receive the NTN configuration and pre-compensated TA value (e.g., T TA ). The UE may calculate the UE-gNB round trip time (RTT) as the TA value (e.g., T TA ) and kmac (scheduling offset). The UE shall delay the start of the RA timer and / or the Discontinuous Reception (DRX) timer by the UE-gNB RTT.

[0504] In addition, the UE shall report the complete TA value (e.g., T TA) and / or UE location. Since the UE pre-compensates the TA value, the NW may need to know the TA value of the UE. The UE will trigger a TA report (TA Report, TAR) based on the configuration of ta-Report and / or offsetThresholdTA. If enabled by an indication (e.g., ta-Report), the UE will trigger TAR in response to connecting to the serving cell. The UE will trigger TAR in response to receiving and / or being configured with a TA threshold (e.g., offsetThresholdTA). The UE will trigger TAR in response to a condition related to a TA threshold (e.g., offsetThresholdTA) being met. TAR will be transmitted via an Opportunity Advance Report MAC CE. More details of TAR can be found in TS 38.321 ([3] 3GPP TS 38.321 V17.5.0) and TS 38.331 ([4] 3GPP TS 38.331 V17.5.0).

[0505] In NTN, the NW on the ground that provides services to the UE may not change, while the satellite between the UE and the NW on the ground may change due to satellite switching or satellite movement. In order to avoid L3 mobility, such as inter-zone handover caused by satellite switching, and to reduce transmission overhead and / or interruption time, an unchanged physical cell identity (PCI) mechanism will be supported in NTN. The unchanged PCI mechanism may be or be referred to as satellite switching, satellite switching without changing PCI, satellite switching with resynchronization, and / or unchanged PCI switching. The unchanged PCI mechanism may be or be referred to as a mechanism without L3 mobility (e.g., inter-zone handover). The satellite switching mechanism avoids L3 mobility of UEs in a cell by maintaining the same PCI over a geographical area. When the satellite switches, the UE can maintain the cell configuration without changing the gNB. Signaling such as inter-zone handover commands can be reduced. The UE should not trigger the RRC reconfiguration procedure. Since the satellite ephemeris (e.g., ephemerisInfo) and / or common TA (e.g., ta-Info) may be different, the UE may perform a resynchronization with the serving cell. The UE may perform DL and / or UL synchronization. The UE may (re)acquire NTN specific system information. In the unchanged PCI mechanism, the UE may switch / change serving satellite without performing a handover, without receiving an RRC (re)configuration, without changing the PCI of the serving cell, and / or without changing the serving gNB.

[0506] Throughout the present disclosure, unchanged PCI switching may be the following (replaced by / equivalent to the following): procedure for unchanged PCI switching, cell switching with resynchronization, satSwitchWithResync, cell switching with unchanged PCI, satellite switching, hard satellite switching, satellite switching without changing PCI, PCI unchanged procedure, procedure for cell switching, procedure for resynchronization, etc., and / or combinations thereof. Throughout the present disclosure, "satellite switching" may be "satellite switching with resynchronization". Throughout the present disclosure, "satellite switching" may be, be referred to as, replace and / or be equivalent to "satellite switching with resynchronization". Fig.17 An example of unchanged PCI and / or satellite switching is shown in (cited in [6] R2-2308373). Fig.17 PCI A and PCI B in are the same PCI.

[0507] The UE may be instructed (by the network) to implement (or initiate) unchanged PCI switching and / or satellite switching. The UE may receive a configuration (or indication) of unchanged PCI switching and / or satellite switching. The configuration (or indication) of unchanged PCI switching and / or satellite switching may instruct the UE to implement (or initiate) unchanged PCI switching and / or satellite switching (e.g., at a specific time, such as t-Service). The configuration may be included in system information (e.g., SIB19). The configuration (or indication) may be satSwitchWithResync. The configuration (or indication) may be included in satSwitchWithResync. The UE may receive at least time information (e.g., t-service) of unchanged PCI switching and / or satellite switching and / or satellite information (e.g., NTN-Config) of the target satellite in system information (e.g., SIB19). Throughout the present disclosure, satSwitchWithResync may be an indication of (enabling / triggering) unchanged PCI switching and / or satellite switching. The UE may receive an indication of (enabling / triggering) unchanged PCI switching and / or satellite switching.

[0508] For example, in response to (receiving) an indication (or configuration), the UE may implement (or initiate) unchanged PCI switching and / or satellite switching. For example, at a specific time, at t-Service, the UE may implement (or initiate) unchanged PCI switching and / or satellite switching. The specific time (or t-Service) may be indicated by the network. The specific time (or t-Service) may be indicated in system information (e.g., SIB19). The specific time (or t-Service) may be (or indicate) a cell stop time. The specific time (or t-Service) may be (or indicate) a time when a cell provided via the NTN stops providing services for the area currently covered by it.

[0509] In response to an unchanged PCI handover and / or a satellite handover (e.g., if an indication of a satellite handover is received, during a satellite handover (procedure), after initiating a satellite handover (procedure), when a satellite handover (procedure) is initiated, and / or at a cell stop time such as t-Service), the UE may:

[0510] - the UL synchronization timer (e.g. T430 for NTN) is considered to have expired;

[0511] (Note: The UL synchronization timer can be different from timeAlignmentTimer.)

[0512] - For example, not used after cell stop time (e.g., t-Service), and / or UE-specific Koffset is not used (if configured) until a new differential Koffset is received (e.g., MAC CE);

[0513] - For example, using a cell-specific Koffset after a cell stop time (e.g., t-Service), and / or using a cell-specific Koffset until a new differential Koffset (e.g., MAC CE) is received;

[0514] -Perform DL (re)synchronization with the serving cell (or NW);

[0515] - (Re)acquire SIB19 (and / or SIB1, SIB2);

[0516] - (re)acquire NTN related configuration (e.g. ephemeris) (e.g. of the serving cell, contained in SIB19);

[0517] - may or may not trigger an RA procedure; and / or

[0518] - UL synchronization with the serving cell (or NW) may or may not be performed.

[0519] (Note: The RA procedure can be a 2-step RA or a 4-step RA.)

[0520] The satellite handover may be RACH-based. The UE may trigger an RA procedure for the satellite handover. The UE may receive a configuration (or indication) indicating that the satellite handover is RACH-based. The UE may receive a configuration (or indication) indicating that the UE performs (or initiates) a RACH-based satellite handover. If the configuration (or indication) indicates that the UE performs (or initiates) a RACH-based satellite handover, the UE triggers an RA procedure for the satellite handover.

[0521] The satellite handover may be RACH-free. The UE may not trigger an RA procedure for the satellite handover. The UE may receive a configuration (or indication) indicating that the satellite handover is RACH-free. The UE may receive a configuration (or indication) indicating that the UE performs (or initiates) a RACH-free satellite handover. If the configuration (or indication) indicates that the UE performs (or initiates) a RACH-free satellite handover, the UE does not trigger an RA procedure for the satellite handover.

[0522] For example, the UE may receive (enable) a first indication of an unchanged PCI mechanism and / or a satellite switch (e.g., satSwitchWithReSync), for example, via a first SIB19. At, before, or after the time information (e.g., t-service), the UE may (start) performing DL synchronization (e.g., with a new satellite, with a serving cell). Before or after the timing indicated by the time information (e.g., t-service), the UE may (start) performing DL synchronization. The UE may consider that the UL synchronization timer (e.g., T430) expires at the time information (e.g., t-service). After DL synchronization, the UE may receive a second SIB19. The second SIB19 includes satellite information after switching the serving satellite. In response to receiving the second SIB19, the UE may start the UL synchronization timer (e.g., T430). In the unchanged PCI mechanism or procedure (or satellite switching procedure), the UE may or may not perform RACH. After DL synchronization, the UE may or may not perform RACH. The unchanged PCI mechanism and / or satellite handover may be RACH-based or RACH-less. SIB 19 may be NTN specific system information.

[0523] The UE will pre-compensate the TA value based on the satellite assistance information in the second SIB19 (e.g., parameters in NTN-Config). However, based on the current mechanism, the UE cannot report the complete TA value to the network after the unchanged PCI switch is implemented. The network cannot know the TA of the UE and / or cannot provide the UE with a UE-specific Koffset. In the case of unchanged PCI switching, it should be defined how the UE triggers or reports its TA value.

[0524] To solve the problem, the UE may trigger a TA report (e.g., for satellite handover) based on the NW configuration. In response to (at least) receiving the NW configuration, the UE may trigger a TA report. Triggering a TA report may include triggering a TA report, indicating (triggering) a lower layer / upper layer of a TA report, calculating a (complete) TA value, generating a TAR MAC CE for a TA report, triggering a Scheduling Request (SR) for a TA report, and / or transmitting a TA report.

[0525] The NW configuration may be an indication of a TA report (e.g., ta-Report). The NW configuration may indicate whether a TA report is triggered (e.g., for satellite switching). The NW configuration may be an indication of a satellite switching (e.g., a first indication) (e.g., satSwitchWithReSync). The NW configuration may indicate whether the UE should initiate a satellite switching, for example, at a specific time (e.g., t-Service). The NW configuration may be an indication of a RACH type (e.g., RACH-based, RACH-free), for example, for satellite switching. The NW configuration may indicate whether a RA procedure is triggered (or initiated) for a satellite switching. The NW configuration may be a new indication related to satellite switching. The NW configuration may be a new indication included / configured in an indication of a satellite switching (e.g., a first indication) (e.g., satSwitchWithReSync).

[0526] Before performing satellite switching, the UE may receive NW configuration in NTN specific system information (eg, SIB19). After performing satellite switching or thereafter, the UE may receive NW configuration in NTN specific system information (eg, SIB19).

[0527] The UE may determine whether to trigger a TA report (e.g., for satellite handover) based on one or more of the following:

[0528] -(Receive) NW configuration;

[0529] -(receive) the first indication (e.g., satSwitchWithReSync);

[0530] - (receive) indication of RACH type (e.g. RACH-based, no-RACH);

[0531] - Satellite switching time information (e.g., t-service);

[0532] -Implement / trigger satellite switching;

[0533] - Implement DL synchronization;

[0534] -Get the system frame number (SFN) information;

[0535] - (receive / acquire) system information (e.g., Master Information Block (MIB), SIB1, SIB19); and / or

[0536] -Implement / trigger RACH (procedure).

[0537] Upon receiving a first indication of satellite switching (e.g., satSwitchWithReSync), after receiving a first indication of satellite switching, in the case of receiving a first indication of satellite switching, or in response to receiving a first indication of satellite switching, the UE may trigger a TA report (e.g., for satellite switching). Upon receiving time information of satellite switching (e.g., t-service), after receiving a time information of satellite switching, in the case of receiving a time information of satellite switching, or in response to receiving a time information of satellite switching, the UE may trigger a TA report (e.g., for satellite switching). Upon performing a satellite switching, upon performing a satellite switching, upon performing a satellite switching, or in response to performing a satellite switching, the UE may trigger a TA report (e.g., for satellite switching). Upon performing, upon performing, upon performing, or in response to performing a DL synchronization, such as with a serving cell, the UE may trigger a TA report (e.g., for satellite switching). The UE may trigger a TA report (e.g., for satellite handover) when, after, in the case of, or in response to a RACH procedure triggering a satellite handover, a RACH procedure triggering a satellite handover.

[0538] If the UE does not receive NW configuration, the UE may not trigger TA reporting for satellite switching. If the UE receives NW configuration, the UE may trigger TA reporting for satellite switching, for example at one of the above occasions.

[0539] If the UE performs a RACH-based satellite handover, the UE may trigger a TA report, for example at one of the above-mentioned occasions. If the UE performs a RACH-free satellite handover, the UE may not trigger a TA report. If the UE performs a RACH-free satellite handover, the UE may trigger a TA report, for example at one of the above-mentioned occasions.

[0540] In one example, the UE may receive, for example, via a first SIB19, a first indication (e.g., satSwitchWithReSync) of (enabling) an unchanged PCI mechanism and / or a satellite switch. At, before, or after the time information (e.g., t-service), the UE may (start) performing DL synchronization (e.g., with a new satellite, with a serving cell). The UE may consider that the UL synchronization timer (e.g., T430) expires at the time information (e.g., t-service). After DL synchronization, the UE may receive a second SIB19. In response to receiving the second SIB19, the UE may start the UL synchronization timer (e.g., T430). The second SIB19 may include a NW configuration for a TA report (e.g., ta-Report). After DL synchronization, the UE may not perform RACH. Based on or if the UE receives an indication of no RACH procedure, for example, together with the first indication (e.g., satSwitchWithReSync), the UE may not perform RACH. After DL synchronization, the UE may trigger a TA report. Based on or if the UE receives NW configuration for TA reporting (eg, ta-Report), the UE may trigger TA reporting.

[0541] In one example, the UE may receive, for example, via a first SIB19, a first indication (e.g., satSwitchWithReSync) of (enabling) an unchanged PCI mechanism and / or a satellite switch. At, before, or after the time information (e.g., t-service), the UE may (start) performing DL synchronization (e.g., with a new satellite, with a serving cell). The UE may consider that the UL synchronization timer (e.g., T430) expires at the time information (e.g., t-service). After DL synchronization, the UE may receive a second SIB19. In response to receiving the second SIB19, the UE may start the UL synchronization timer (e.g., T430). The second SIB19 may not include a NW configuration for a TA report (e.g., ta-Report). After DL synchronization, the UE may perform RACH. Based on or if the UE receives an indication of a RACH-based procedure, for example, together with the first indication (e.g., satSwitchWithReSync), the UE may perform RACH. Based on or if the UE does not receive an indication of no RACH procedure, for example together with the first indication (e.g., satSwitchWithReSync), the UE may perform RACH. The UE may trigger the RACH procedure. After DL synchronization, the UE may not trigger TA reporting. In response to, in the case of, after, or after triggering the RACH procedure, the UE may not trigger TA reporting. Based on or if the UE does not receive an NW configuration for TA reporting (e.g., ta-Report), the UE may not trigger TA reporting.

[0542] If TA reporting is triggered, the UE may generate a TAR MAC CE, for example if UL Shared Channel (SCH) resources are available for new transmission and due to logical channel prioritization the UL-SCH resources can accommodate the TAR MAC CE plus its subheader.

[0543] If TA reporting is triggered, the UE may trigger a scheduling request, for example if the UE receives a configuration (eg, timingAdvanceSR, with the value enabled).

[0544] Upon receiving NTN specific system information (e.g., SIB19), the UE shall start or restart a validity timer (e.g., T430) with a validity duration (e.g., ntn-UlSyncValidityDuration) starting from the subframe indicated by the free epoch time (e.g., epochTime). Before the validity timer expires / expires, the UE may obtain the NTN specific system information (e.g., SIB19). The UE shall apply the epoch time (e.g., epochTime) as the start timing of the validity timer after / after receiving the NTN specific system information (e.g., SIB19). The UE shall apply the validity duration (e.g., ntn-UlSyncValidityDuration) as the length of the validity timer. The validity duration (e.g., ntn-UlSyncValidityDuration) and / or the validity timer (e.g., T430) may indicate the duration when the satellite information or a part of the satellite information (e.g., ephemerisInfo, ta-Info) is valid. Upon expiration of the validity timer in RRC connected mode, the UE may then consider that uplink synchronization has been lost and / or acquire NTN-specific system information (e.g., SIB19). In response to acquiring NTN-specific system information (e.g., SIB19), the UE may consider that uplink synchronization has been acquired. If uplink synchronization is considered to have been lost, the UE may clear the hybrid automatic repeat request (HARQ) buffer and may not perform UL transmission on the serving cell. If uplink synchronization is deemed to have been acquired, the UE may perform UL transmission on the serving cell. When the validity timer is in operation, the serving cell may be considered to have achieved uplink synchronization in RRC connected mode (e.g., uplink synchronization has been acquired). When the validity timer is not in operation and / or expires, the serving cell may be considered to have not achieved uplink synchronization in RRC connected mode (e.g., uplink synchronization has been lost). The validity timer (e.g., T430) may be a UL synchronization timer.

[0545] For unchanged PCI switching and / or satellite switching (with resynchronization), the UE shall perform DL synchronization and UL synchronization with the target satellite. The network may resume transmission after the satellite switching. The UE may receive an indication of the satellite switching (e.g., satSwitchWithReSync) and time information (e.g., t-service). When the UE performs UL synchronization, the UE shall consider that UL synchronization with the current satellite has been lost (e.g., by considering T430 expired) and then consider that UL synchronization with the target satellite has been acquired. The UE may consider that the validity timer (e.g., T430) has expired at the time information (e.g., t-service). According to current specifications (e.g., [3] 3GPP TS 38.321 V17.5.0 and [4] 3GPP TS 38.331 V17.5.0), the UE shall clear all HARQ buffers immediately after UL synchronization is lost. However, for the case of satellite switching, clearing the HARQ buffers may cause a delay in transmission due to the fact that HARQ retransmission cannot be performed after the satellite switching.

[0546] In the present invention, in response to unchanged PCI switching (or satellite switching), the UE may not clear one or more HARQ buffers. The indication of UL synchronization loss may be differentiated based on the cause (e.g., satellite switching, T430 expiration). When UL synchronization has been lost, the UE determines whether to clear one or more HARQ buffers based on whether the UL synchronization loss is caused by satellite switching. If the UL synchronization loss is caused by satellite switching, the UE stops UL transmission and / or does not clear one or more HARQ buffers. If the UL synchronization loss is not caused by satellite switching (e.g., caused by T430 expiration), the UE stops UL transmission and clears one or more HARQ buffers.

[0547] During the procedure of unchanged PCI switching (or satellite switching), the UE may not clear the HARQ buffer. Based on (at least) the first condition, the UE may not clear the HARQ buffer. Based on (at least) the first condition, the UE may not perform any uplink transmission on the serving cell. The first condition may be one or more of the following:

[0548] - if an indication of uplink synchronization loss is received from upper layers due to T430 expiring at the time information (e.g., t-service);

[0549] - if an indication of uplink synchronization loss is received from upper layers for a satellite handover;

[0550] - if an indication of uplink synchronization loss caused by satellite handover is received from upper layers;

[0551] - if an indication of uplink synchronization loss is received from upper layers during satellite handover;

[0552] - (if an indication of uplink synchronization loss is received from upper layers, and) if a satellite handover procedure is in progress;

[0553] - (if an indication of uplink loss of synchronization is received from upper layers, and) if a first indication of a satellite mechanism (e.g. satSwitchWithReSync) has been received / configured (enabled); and / or

[0554] - (If an indication of uplink loss of synchronization is received from upper layers, and) if the first indication of the satellite mechanism (e.g. satSwitchWithReSync) is present (enabled) in SIB19.

[0555] Based on (at least) the second condition, the UE may clear (all) HARQ buffers. Based on (at least) the second condition, the UE may not perform any uplink transmission on the serving cell. The second condition may be one or more of the following:

[0556] - if an indication of uplink synchronization loss is received from upper layers other than due to T430 expiring at the time information (e.g. t-service);

[0557] - if an indication of uplink synchronization loss is received from upper layers other than for satellite handover;

[0558] - if an indication of uplink synchronization loss (not caused by satellite handover) is received from upper layers;

[0559] - if an indication of uplink synchronization loss is not received from upper layers during satellite handover;

[0560] - (if an indication of loss of uplink synchronization is received from upper layers, and) if a satellite handover procedure is not in progress;

[0561] - (if an indication of uplink loss of synchronization is received from upper layers, and) if the first indication of a satellite mechanism (e.g. satSwitchWithReSync) has not been received / configured (enabled); and / or

[0562] - (If an indication of uplink loss of synchronization is received from upper layers, and) if the first indication of the satellite mechanism (e.g. satSwitchWithReSync) is not present (enabled) in SIB19.

[0563] In response to a satellite handover (e.g., if an indication of a satellite handover is received, during a satellite handover, after initiating a satellite handover, when a satellite handover is initiated, if a satellite handover is initiated, and / or during a cell outage time such as t-Service), the UE may:

[0564] - Do not clear the (UL) HARQ buffer (or all HARQ buffers) (eg, for one serving cell, for all serving cells).

[0565] The HARQ buffer may be associated with a HARQ process. The UE may perform an initial transmission associated with the HARQ process (e.g., before satellite switching). The UE may perform a retransmission (e.g., HARQ retransmission) associated with the HARQ process (e.g., after satellite switching).

[0566] The UE (e.g., a MAC entity of the UE) may receive an indication of uplink synchronization loss from an upper layer (e.g., an RRC layer). In response to receiving the indication of uplink synchronization loss, the UE may not perform uplink transmission on the serving cell and / or may determine whether to clear the HARQ buffer based on whether the uplink synchronization loss is caused by satellite switching. Regardless of whether the uplink synchronization loss is caused by satellite switching, the UE may not perform uplink transmission on the serving cell. Regardless of the cause of UL synchronization loss, the UE may not perform uplink transmission on the serving cell. When the UE does not perform uplink transmission on the serving cell, the UE may stop and / or suspend UL transmission on the serving cell. Based on the cause of UL synchronization loss, the UE may determine whether to clear the HARQ buffer. The cause of UL synchronization loss may include satellite switching. The cause of UL synchronization loss may include T430 expiration. In response to receiving the indication of uplink synchronization loss, the UE may perform (e.g., a determination as to whether to clear the HARQ buffer and / or whether the uplink synchronization loss is caused by satellite switching). If (at least) the uplink synchronization loss is caused by satellite switching, the UE may not clear the HARQ buffer. If (at least) the uplink synchronization loss is not caused by satellite switching, the UE may clear the HARQ buffer. If (at least) the uplink synchronization loss is caused by T430 expiration, the UE may clear the HARQ buffer.

[0567] For example, the UE may receive system information (from a serving cell), wherein the system information includes at least an indication of a satellite switch. The system information may be SIB19. The indication of the satellite switch may be satSwitchWithResync. Based on the indication of the satellite switch being included in the system information, the UE may initiate a procedure for satellite switching (with resynchronization). In response to initiating the procedure for satellite switching, the UE may indicate that uplink synchronization is lost. For example, in response to the uplink synchronization loss, the UE may not perform uplink transmission on the serving cell. The UE may stop or suspend uplink transmission on the serving cell. For example, in response to the uplink synchronization loss, based on the fact that the uplink synchronization loss is caused by a satellite switch, the UE may not clear the HARQ buffer.

[0568] For example, upon receiving the system information (from the serving cell), the UE may start or restart the timer. The timer may be T430. The system information may be SIB19. In response to the expiration of the timer, the UE may indicate that uplink synchronization is lost. For example, in response to the uplink synchronization loss, the UE may not perform uplink transmission on the serving cell. The UE may stop or suspend uplink transmission on the serving cell. For example, in response to the uplink synchronization loss, based on the uplink synchronization loss not being caused by satellite handover, the UE may clear the HARQ buffer.

[0569] The UE may perform different actions (eg, at least one or more of the actions mentioned above) for RACH-based satellite handover and RACH-free satellite handover.

[0570] Based on whether the satellite handover is RACH-based or RACH-free, the UE may determine whether to perform at least one or more of the above actions.

[0571] For example, the UE may: if the satellite switching is RACH-based, perform at least one or more of the above actions in response to the satellite switching; and / or if the satellite switching is RACH-free, do not perform at least one or more of the above actions in response to the satellite switching.

[0572] For example, the UE may: if the satellite switching is RACH-free, perform at least one or more of the above actions in response to the satellite switching; and / or if the satellite switching is RACH-based, not perform at least one or more of the above actions in response to the satellite switching.

[0573] Different actions can be determined separately.

[0574] For example, the UE may: if the satellite handover is RACH-based, perform the first action but not the second action in response to the satellite handover; and / or if the satellite handover is RACH-free, perform the second action but not the first action in response to the satellite handover.

[0575] For example, the UE may: if the satellite handover is RACH-free, perform the first action but not the second action in response to the satellite handover; and / or if the satellite handover is RACH-based, perform not the first action but the second action in response to the satellite handover.

[0576] Any of the embodiments, concepts, methods, examples, behaviors and / or events described above and herein may be combined in whole or in part, or applied simultaneously or separately.

[0577] The UE may receive NTN-related configurations (eg, SIB19, NTN-Config). The UE may be configured with multiple connectivity, carrier aggregation (CA), dual connectivity (DC), SCell and / or secondary cell group (SCG).

[0578] The UE may be in a cell of NTN and / or a cell of TN. The UE may be connected to a cell of NTN and / or a cell of TN. The UE may reside on a cell of NTN and / or a cell of TN. The UE may be connected to LEO, GEO, MEO, HEO, ATG and / or HAPS. The UE may be connected to one or two networks (nodes). Throughout this disclosure, a cell may be or may refer to an NTN cell or a TN cell.

[0579] UE may be referred to as UE, RRC layer of UE, MAC entity of UE or physical layer of UE.

[0580] The UE may be a NR device. The UE may be a Long Term Evolution (LTE) device. The UE may be a NarrowBand Internet of Things (NB-IoT) device. The UE may be an Enhanced Machine-Type Communication (eMTC) device. The UE may be an under-capable device. The UE may be a mobile phone. The UE may be a wearable device. The UE may be a sensor. The UE may be a fixed device. The UE may be an (unmanned) aerial vehicle.

[0581] The network may be a base station. The network may be an access point. The network may be an eNB. The network may be a gNB. The network may be a gateway.

[0582]

[00136] To the extent possible of the methods, alternatives, concepts, examples and embodiments described above and in detail herein, the following aspects and embodiments are possible.

[0583] refer to Fig.18 , utilizing this and other concepts, systems and methods of the present invention, a method 1000 for a UE in a wireless communication system includes: receiving a first indication of a satellite handover (step 1002); performing DL synchronization with a serving cell at an opportunity (step 1004); receiving NTN-specific system information (step 1006); after performing DL synchronization with the serving cell, determining whether to trigger a TA report based on whether the indication is provided by the network (step 1008); and triggering a TA report if the indication is provided by the network in the NTN-specific system information (step 1010).

[0584] In various embodiments, the UE does not perform a RACH procedure.

[0585] In various embodiments, the UE receives a second indication of no RACH.

[0586] In various embodiments, the NTN specific system information is SIB19.

[0587] In various embodiments, the first indication is satSwitchWithReSync.

[0588] In various embodiments, the indication is a ta-Report.

[0589] In various embodiments, the timing is indicated by time information of the satellite switching.

[0590] Return to reference Figure 3 and 4 In one or more embodiments from the perspective of a UE in a wireless communication system, the apparatus 300 includes program code 312 stored in a memory 310 of a transmitter. The CPU 308 may execute the program code 312 to: (i) receive a first indication of a satellite handover; (ii) perform DL synchronization with a serving cell at an opportunity; (iii) receive NTN-specific system information; (iv) after performing DL synchronization with a serving cell, determine whether to trigger a TA report based on whether the indication is provided by the network; and (v) if the indication is provided by the network in the NTN-specific system information, trigger a TA report. In addition, the CPU 308 may execute the program code 312 to perform all of the described actions, steps, and methods described above, below, or otherwise herein.

[0591] Return to reference Figure 3 and 4In one or more embodiments, from the perspective of the NW in the wireless communication system, the apparatus 300 includes program code 312 stored in the memory 310 of the transmitter. The CPU 308 can execute the program code 312 to: (i) transmit a first indication of satellite switching to the UE; (ii) transmit NTN-specific system information to the UE; (iii) transmit an indication of triggering a TA report to the UE; and (iv) receive a TA report from the UE if the indication is transmitted to the UE. In addition, the CPU 308 can execute the program code 312 to implement all described actions, steps, and methods described above, below, or otherwise herein.

[0592] In [8]R2-2307623, it is proposed to discuss whether the timeAlignmentTimer is considered to expire at t-Service:

[0593]

[0594] For unchanged PCI handover (or satellite handover), if timeAlignmentTimer is deemed expired (e.g., at t-Service), the following UE actions shall be taken immediately after expiration of timeAlignmentTimer (e.g., at t-Service), as specified in the current NR MAC specification (e.g., [3] 3GPP TS 38.321 V17.5.0):

[0595] - Clear (all) HARQ buffers (for all serving cells);

[0596] - (notify RRC) release the Physical Uplink Control Channel (PUCCH) (for all serving cells, if configured);

[0597] - (notify RRC) release Sounding Reference Signal (SRS) (for all serving cells, if configured);

[0598] - clear (any) configured downlink assignments;

[0599] - clear (any) configured uplink grants; and

[0600] - Clear (any) Physical Uplink Shared Channel (PUSCH) resources used for semi-persistent CSI reporting.

[0601] And when timeAlignmentTimer expires, after MAC notifies RRC, the following UE actions will be performed as specified in the current NR RRC specification (e.g., [4] 3GPP TS 38.331 V17.5.0):

[0602] Upon receiving a PUCCH release request from lower layers, the UE shall (for all bandwidth parts of the indicated serving cell):

[0603] Release the PUCCH-CSI-Resource configured in the Channel State Information (CSI)-ReportConfig; and

[0604] Release the SchedulingRequestResourceConfig instance configured in PUCCH-Config.

[0605] Upon receiving an SRS release request from lower layers, the UE shall (for all bandwidth parts of the indicated serving cell):

[0606] Release the SRS-Resource instance configured in SRS-Config.

[0607] However, satellite handover is mainly used in the scenario where satellite handover is performed without changing gNB, and the benefit of satellite handover (compared to handover) is that transmission overhead is saved by not having to send RRC reconfiguration messages to the UE. It is considered that as a result of the expiration of timeAlignmentTimer (e.g., at t-Service) in satellite handover, the NW needs to transmit RRC reconfiguration messages (and / or) other signaling (e.g., MAC CE / Physical Downlink Control Channel (PDCCH) for activation, etc.) to reconfigure (and / or activate) PUCCH, SRS, configured downlink assignments, configured uplink grants, and / or PUSCH resources for semi-persistent CSI reporting later (e.g., after satellite handover). In this case, the benefit of reduced transmission overhead caused by satellite handover is minimized.

[0608] To address the issue, in response to an unchanged PCI switch or a satellite switch (e.g., if an indication of a satellite switch is received, during a satellite switch (procedure), after initiating a satellite switch (procedure), when a satellite switch (procedure) is initiated, and / or if a satellite switch (procedure) is initiated), the UE may maintain: timeAlignmentTimer (from expiration), PUCCH resources and / or configuration, SRS resources and / or configuration, configured downlink assignments, configured uplink grants, and / or PUSCH resources for semi-persistent CSI reporting. In response to a satellite switch (e.g., if an indication of a satellite switch is received, during a satellite switch (procedure), and / or if a satellite switch (procedure) is initiated), the UE may maintain and / or may not release the following configurations and / or resources: PUCCH resources / configuration, SRS resources / configuration, configured downlink assignments, configured uplink grants, and / or PUSCH resources for semi-persistent CSI reporting.

[0609] In response to a satellite handover (e.g., if an indication of a satellite handover is received, during a satellite handover (procedure), after initiating a satellite handover (procedure), when a satellite handover (procedure) is initiated, and / or if a satellite handover (procedure) is initiated, at a cell stop time such as t-Service), the UE may:

[0610] - The time alignment timer is not considered to have expired;

[0611] - not performing at least one or more actions that are to be performed when the time alignment timer expires;

[0612] - Continue the time alignment timer (or keep the time alignment timer running);

[0613] - The time alignment timer is considered to be running;

[0614] - stopping (or pausing) the time alignment timer (e.g. if running); and / or

[0615] - Start (or restart) the time alignment timer.

[0616] The time alignment timer may be associated with the PTAG of the UE. The time alignment timer may be timeAlignmentTimer.

[0617] The UE may start (or resume) the time alignment timer when / if / after / in response to at least one or more of the following occurs:

[0618] -(Successfully) Completed satellite switching;

[0619] - (Successful) completion of the RA procedure;

[0620] - RAR (Random Access Response) received;

[0621] - receiving a timing advance command, for example contained in a RAR;

[0622] - Apply the (updated) TA value;

[0623] - Get the (updated) SIB19 (of the serving cell);

[0624] - obtain the (updated) ephemeris (of the serving cell); and / or

[0625] -Perform UL and / or DL ​​synchronization with the serving cell.

[0626] When the time alignment timer expires, at least one or more actions are performed by the UE. The at least one or more actions may include:

[0627] - Clear a HARQ buffer (or all HARQ buffers) (e.g., for all serving cells);

[0628] - (notify RRC) release PUCCH (e.g., PUCCH resources and / or configuration, for all serving cells, if configured);

[0629] - (notify RRC) release SRS (e.g., SRS resources and / or configuration, for all serving cells, if configured);

[0630] - Clear the configured downlink assignment (or any configured downlink assignment);

[0631] - Clear a configured uplink grant (or any configured uplink grant);

[0632] - Clear (any) PUSCH resources used for semi-persistent CSI reporting;

[0633] - Release the PUCCH-CSI-Resource configured in CSI-ReportConfig (e.g., all bandwidth parts for the indicated serving cell);

[0634] - releasing the SchedulingRequestResourceConfig instance configured in PUCCH-Config (e.g., for all bandwidth parts of the indicated serving cell); and / or

[0635] - Release the SRS-Resource instance configured in the SRS-Config (eg, for all bandwidth parts of the indicated serving cell).

[0636] In response to a satellite handover (e.g., if an indication of a satellite handover is received, during a satellite handover (procedure), after initiating a satellite handover (procedure), when a satellite handover (procedure) is initiated, and / or if a satellite handover (procedure) is initiated, at a cell stop time such as t-Service), the UE may:

[0637] - PUCCH (e.g., PUCCH resources and / or configuration) is not released;

[0638] - Maintain (or continue to apply or use) the current (configured) PUCCH resources and / or configuration; and / or

[0639] - Suspend PUCCH resources and / or configuration.

[0640] The UE may restore PUCCH resources and / or configuration when / if / after / in response to at least one or more of the following occurs:

[0641] -(Successfully) Completed satellite switching;

[0642] - (Successful) completion of the RA procedure;

[0643] - RAR (Random Access Response) received;

[0644] - receiving a timing advance command, for example contained in a RAR;

[0645] - Apply the (updated) TA value;

[0646] - Get the (updated) SIB19 (of the serving cell);

[0647] - obtain the (updated) ephemeris (of the serving cell); and / or

[0648] -Perform UL and / or DL ​​synchronization with the serving cell.

[0649] PUCCH resources and / or configuration may be (or include):

[0650] -PUCCH-Config (and / or configuration in PUCCH-Config);

[0651] -PUCCH resources (and / or resource sets);

[0652] - PUCCH resources for scheduling requests;

[0653] - PUCCH resources for CSI reporting;

[0654] - PUCCH-CSI-Resource configured in CSI-ReportConfig (e.g., for all bandwidth parts of the indicated serving cell); and / or

[0655] - SchedulingRequestResourceConfig instance configured in PUCCH-Config (eg, for all bandwidth parts of the indicated serving cell).

[0656] In response to a satellite handover (e.g., if an indication of a satellite handover is received, during a satellite handover (procedure), after initiating a satellite handover (procedure), when a satellite handover (procedure) is initiated, and / or if a satellite handover (procedure) is initiated, at a cell stop time such as t-Service), the UE may:

[0657] - not releasing the SRS (e.g., SRS resources and / or configuration);

[0658] - Maintain (or continue to apply or use) the current (configured) SRS resources and / or configuration; and / or

[0659] -Suspend SRS resources and / or configuration.

[0660] The UE may restore SRS resources and / or configuration when / if / after / in response to at least one or more of the following:

[0661] -(Successfully) Completed satellite switching;

[0662] - (Successful) completion of the RA procedure;

[0663] - RAR (Random Access Response) received;

[0664] - receiving a timing advance command, for example contained in a RAR;

[0665] - Apply the (updated) TA value;

[0666] - Get the (updated) SIB19 (of the serving cell);

[0667] - obtain the (updated) ephemeris (of the serving cell); and / or

[0668] -Perform UL and / or DL ​​synchronization with the serving cell.

[0669] SRS resources and / or configurations may be (or include):

[0670] -SRS-config (and / or configuration in PUCCH-Config);

[0671] - PUCCH resources (and / or resource sets); and / or

[0672] -SRS-Resource instance configured in SRS-Config.

[0673] In response to a satellite handover (e.g., if an indication of a satellite handover is received, during a satellite handover (procedure), after initiating a satellite handover (procedure), when a satellite handover (procedure) is initiated, and / or if a satellite handover (procedure) is initiated, at a cell stop time such as t-Service), the UE may:

[0674] - does not clear the configured downlink assignment (or any configured downlink assignment);

[0675] - Maintain (or continue to apply or use) the current (configured) resources and / or configuration of the configured downlink assignment;

[0676] - suspending the resources and / or configuration of the configured downlink assignment;

[0677] - does not clear the configured uplink grant (or any configured uplink grant);

[0678] - Maintain (or continue to apply or use) the current (configured) resources and / or configuration of the configured uplink grant;

[0679] - suspending the resources and / or configuration of the configured uplink grant; and / or

[0680] - A configured uplink grant and / or a configured downlink assignment is considered deactivated.

[0681] The UE may restore (or activate) the configured downlink assignment and / or configured uplink granted resources and / or configuration when / if / after / in response to at least one or more of the following:

[0682] -(Successfully) Completed satellite switching;

[0683] - (Successful) completion of the RA procedure;

[0684] - RAR (Random Access Response) received;

[0685] - receiving a timing advance command, for example contained in a RAR;

[0686] - Apply the (updated) TA value;

[0687] - Get the (updated) SIB19 (of the serving cell);

[0688] - obtain the (updated) ephemeris (of the serving cell); and / or

[0689] -Perform UL and / or DL ​​synchronization with the serving cell.

[0690] The configured uplink grant may be a configured grant type 1. The configured uplink grant may be a configured grant type 2. The configured downlink assignment may be DL Semi-Persistent Scheduling (SPS).

[0691] Configured grants Type 1 and Type 2 may be handled differently in satellite handover.

[0692] In response to a satellite handover (e.g., if an indication of a satellite handover is received, during a satellite handover (procedure), after initiating a satellite handover (procedure), when a satellite handover (procedure) is initiated, and / or if a satellite handover (procedure) is initiated, at a cell stop time such as t-Service), the UE may:

[0693] - not clearing one (or any) PUSCH resource used for semi-persistent CSI reporting;

[0694] - Maintain (or continue to apply or use) the current (configured) PUSCH resources for semi-persistent CSI reporting; and / or

[0695] - Suspend (PUSCH resources used for) semi-persistent CSI reporting.

[0696] The UE may resume (the PUSCH resources for) semi-persistent CSI reporting when / if / after / in response to at least one or more of the following:

[0697] -(Successfully) Completed satellite switching;

[0698] - (Successful) completion of the RA procedure;

[0699] - RAR (Random Access Response) received;

[0700] - receiving a timing advance command, for example contained in a RAR;

[0701] - Apply the (updated) TA value;

[0702] - Get the (updated) SIB19 (of the serving cell);

[0703] - obtain the (updated) ephemeris (of the serving cell); and / or

[0704] -Perform UL and / or DL ​​synchronization with the serving cell.

[0705] Suspending a resource and / or configuration may be (or include) stopping using (or applying) the resource and / or configuration (temporarily, for example, for a certain period of time until it is resumed). When a resource and / or configuration is suspended, the resource and / or configuration is retained (or not released).

[0706] Resuming resources and / or configurations may be (or include) starting to use (or apply) the (paused) resources and / or configurations.

[0707]

[00136] To the extent possible of the methods, alternatives, concepts, examples and embodiments described above and in detail herein, the following aspects and embodiments are possible.

[0708] refer to Fig.19 , utilizing this and other concepts, systems and methods of the present invention, a method 1020 for a UE in a wireless communication system includes: receiving a configuration for a satellite handover (step 1022); initiating a satellite handover at an opportunity (step 1024); in response to the satellite handover, performing DL and / or UL (re)synchronization with a serving cell (step 1026); in response to the satellite handover, (re)acquiring system information related to the NTN (step 1028); and in response to the satellite handover, not considering the time alignment timer to have expired (step 1030).

[0709] In various embodiments, in response to the satellite switch, the UE stops or pauses the time alignment timer.

[0710] In various embodiments, in response to the satellite switch, the UE does not clear one or more HARQ buffers associated with the HARQ process.

[0711] In various embodiments, in response to satellite switching, the UE maintains (or suspends) PUCCH resources and / or configurations.

[0712] In various embodiments, PUCCH resources and / or configurations are used for scheduling requests.

[0713] In various embodiments, PUCCH resources and / or configurations are used for CSI reporting.

[0714] In various embodiments, in response to satellite switching, the UE maintains (or suspends) SRS resources and / or configurations.

[0715] In various embodiments, in response to the satellite handoff, the UE maintains (or suspends) a configured uplink grant and / or a configured downlink assignment.

[0716] In various embodiments, in response to satellite switching, the UE maintains (or suspends) CSI reporting.

[0717] In various embodiments, the configuration of the satellite switching is an indication of a change in enabled satellites.

[0718] In various embodiments, the timing is indicated by a cell out-of-service time.

[0719] In various embodiments, the timing is indicated by the configuration of the satellite switching.

[0720] Return to reference Figure 3 and 4 In one or more embodiments from the perspective of a UE in a wireless communication system, the apparatus 300 includes program code 312 stored in a memory 310 of a transmitter. The CPU 308 may execute the program code 312 to: (i) receive a configuration of a satellite handover; (ii) initiate a satellite handover at an opportunity; (iii) perform DL and / or UL (re)synchronization with a serving cell in response to the satellite handover; (iv) (re)acquire system information related to the NTN in response to the satellite handover; and (v) do not consider a time alignment timer to have expired in response to the satellite handover. In addition, the CPU 308 may execute the program code 312 to perform all of the described actions, steps, and methods described above, below, or otherwise herein.

[0721] The UE shall use timers (e.g., UL synchronization timer, validity timer) to maintain UL synchronization (e.g., for a serving cell) and / or validity of NTN information based on NTN information. The UE shall start or restart an UL synchronization timer (e.g., T430) with a validity duration (e.g., ntn-UlSyncValidityDuration) from the subframe indicated by the corresponding epoch time (e.g., epochTime), wherein the validity duration (e.g., ntn-UlSyncValidityDuration) and the epoch time (e.g., epochTime) are provided for the serving cell. The UE shall apply the epoch time (e.g., epochTime) as the start timing of the UL synchronization timer (e.g., T430). The UE shall apply the validity duration (e.g., ntn-UlSyncValidityDuration) as the length of the UL synchronization timer (e.g., T430). The UL synchronization timer (e.g., T430) may be started and / or run based on, for example, NTN information of the serving cell. The validity duration (eg, ntn-UlSyncValidityDuration) and / or the UL synchronization timer (eg, T430) may indicate a duration when the satellite information or a portion of the satellite information (eg, ephemerisInfo, ta-Info) is valid.

[0722] For example, when the UL synchronization timer (e.g., T430) is running, (a portion of) the satellite information may be considered valid. When the UL synchronization timer (e.g., T430) is not running, (a portion of) the satellite information may be considered invalid. The UL synchronization timer (e.g., T430) may indicate a duration for acquiring or maintaining UL synchronization based on the satellite information or a portion of the satellite information (e.g., ephemerisInfo, ta-Info).

[0723] For example, when the UL synchronization timer (e.g., T430) is running, the UL may be considered to be in synchronization, or UL synchronization may be considered to be acquired. When the UL synchronization timer (e.g., T430) has been started, the UL may be considered to be in synchronization, or UL synchronization may be considered to be acquired. In response to starting the UL synchronization timer (e.g., T430), the UE may (consider / consider as acquired) UL synchronization. When the UL synchronization timer (e.g., T430) is not running, the UL may be considered to be out of synchronization, or UL synchronization may be considered to be lost. When the UL synchronization timer (e.g., T430) is stopped and / or (considered to be) expired, the UL may be considered to be out of synchronization, or UL synchronization may be considered to be lost. In response to stopping the UL synchronization timer (e.g., T430), the UE may regard UL synchronization as lost / considered to be lost, and / or consider that UL synchronization loss has occurred.

[0724] Based on current specifications (e.g., [3] 3GPP TS 38.321 V17.5.0 and [9] 3GPP TS 38.331 V17.6.0), upon receiving SIB19, the UE immediately starts the UL synchronization timer (e.g., T430) based on the NTN configuration of the serving cell. In response to receiving a handover command (e.g., RRCReconfiguration and ReconfigurationWithSync), the UE stops the UL synchronization timer (e.g., T430) and then starts the UL synchronization timer (e.g., T430). When the UE performs and / or implements a handover (or reconfiguration with synchronization), the UE stops the UL synchronization timer (e.g., T430). Then, the UE starts the UL synchronization timer (e.g., T430) based on the NTN configuration of the target cell.

[0725] The UE will reacquire SIB19 before the UL synchronization timer expires. After the UL synchronization timer expires in RRC connected mode, the UE may then consider that uplink synchronization has been lost and acquire SIB19. In response to acquiring SIB19, the UE may consider that uplink synchronization has been acquired. If uplink synchronization is deemed to be lost, the UE may clear the HARQ buffer and may not perform UL transmission on the serving cell. If uplink synchronization is deemed to be acquired, the UE may perform UL transmission on the serving cell. When the UL synchronization timer is running, the serving cell may be considered to have achieved uplink synchronization in RRC connected mode (e.g., uplink synchronization has been acquired). When the UL synchronization timer is not running and / or expires, the serving cell may be considered to have not achieved uplink synchronization in RRC connected mode (e.g., uplink synchronization has been lost).

[0726] Throughout the present disclosure, the UL synchronization timer may be a timer for a serving cell (or source cell). The UL synchronization timer may be a UL synchronization timer for a target cell (or neighboring cell). The UL synchronization timer may be a validity timer. The UL synchronization timer may be a timer T430. The UL synchronization timer may be used to maintain / evaluate UL synchronization, such as when the UE is in an NTN, when the UE is connected to a satellite. The UL synchronization timer may indicate / process the duration when (associated) assistance information is valid. The UL synchronization timer may indicate / process the duration when the UE may apply (associated) satellite information, such as without acquiring new satellite information. The UL synchronization timer may be used in an NTN. The UL synchronization timer (e.g., T430) may not be used in a TN. The UL synchronization timer (e.g., T430) may be a timer specific to an NTN. The UL synchronization timer may be different from a TA timer (e.g., TimeAlignmentTimer). The UL synchronization timer may not be used to maintain the UL TA. The UL synchronization timer may be associated with a cell. The UL synchronization timer may not be associated with a TA group. When the (associated) satellite information is valid, the UE may consider the UL to be synchronized.

[0727] For example, in response to (receiving) an indication (e.g., satSwitchWithReSync), in response to receiving system information containing an indication (e.g., satSwitchWithReSync), the UE may implement (or initiate) an unchanged PCI handover or a satellite handover. For example, at a specific time, at t-Service, before t-Service, after t-Service, after t-Start, after receiving system information, the UE may implement (or initiate) an unchanged PCI handover or a satellite handover. The specific time may be indicated by the network. The specific time may be indicated in system information (e.g., SIB19). The specific time may be (or indicate) a cell stop time (e.g., t-Service). The specific time may be (or indicate) a handover start time (e.g., t-Start). The cell stop time (e.g., t-Service) may be (or indicate) the time when a cell provided via the NTN will stop providing services for the area currently covered by it. The handover start time (e.g., t-Start) may be (or indicate) the time when the second satellite will provide services for the area (or cell) currently covered or provided by the first satellite. The handover start time (e.g., t-Start) may be (or indicate) the time when the unchanged PCI handover or satellite handover may be started or implemented. Throughout the present disclosure, t-Start may be the handover start time, and t-Service may be the cell stop time. Throughout the present disclosure, t-Start may be represented by t-Service minus t-Gap.

[0728] The unchanged PCI handover or satellite handover may be or include a soft satellite handover and / or a hard satellite handover. The soft satellite handover or the hard satellite handover may be indicated explicitly or implicitly by the NW. The NW may provide an indication of the satellite handover type (e.g., soft satellite handover or hard satellite handover). The NW may provide t-Start and / or SSB information for the soft satellite handover. The indication may be a parameter, t-Start and / or SSB information.

[0729] For a hard satellite handover, the UE may connect to (or synchronize with) a new satellite (e.g., a target satellite, a second satellite) after disconnecting from the old satellite (e.g., a source satellite, a first satellite). Fig. 20 (cited in

[10] R2-2310307) and Fig.21 The service satellite can be at a point in time (e.g., Fig. 20 The switching time in the first satellite (for example, t-Service) is switched. The time point may be t-Service. Fig. 20 The second satellite (e.g., SAT1) may be a serving satellite before the satellite switching and / or time point. Fig. 20 The SAT2 in (SAT2) may be a serving satellite after the satellite switching and / or time point. The first satellite and the second satellite may provide services for the same cell (e.g., have the same PCI). The first satellite may be a source satellite. The second satellite may be a target satellite. The UE may receive (enable) a first indication of an unchanged PCI mechanism or a satellite switching (e.g., satSwitchWithReSync) via a first SIB19. In response to receiving the first SIB19, the UE may start or restart a UL synchronization timer (e.g., T430). The UE may stop transmitting to the first satellite at t-Service and start acquiring / implementing DL synchronization with the second satellite after t-Service. The UE may consider that the UL synchronization timer (e.g., T430) expires at t-Service. After DL synchronization, for example, in response to the expiration of the UL synchronization timer (e.g., T430), the UE may acquire a second SIB19. The second SIB19 includes satellite information after switching the serving satellite. In response to receiving the second SIB19, for example, based on the satellite information, the UE may start a UL synchronization timer (e.g., T430). After DL synchronization and when the UL synchronization timer (e.g., T430) is running, the UE may perform a RA procedure or not perform a RA procedure, for example, based on the NW indication. When the UL synchronization timer (e.g., T430) is running and / or when the RA procedure is performed, after DL synchronization, the UE may acquire UL synchronization with the second satellite.

[0730] For soft satellite handover, the UE may connect to (or synchronize with) a new satellite (e.g., a target satellite, a second satellite) before disconnecting from the old satellite (e.g., a source satellite, a first satellite). Fig. 22 (cited in

[10] R2-2310307) and Fig.23 The service satellite can be in the duration (e.g., Fig. 22 The first satellite (e.g., Fig. 22 SAT1 in) and the second satellite (e.g., Fig. 22 The first satellite may be a serving satellite before the satellite switching and / or t-Start. The second satellite (e.g., SAT2) may provide service / coverage for the same area during the duration. The duration may start at t-Start and end at t-Service. Fig. 20 SAT2 in (SAT2) may be a serving satellite after satellite switching and / or t-Service. The first satellite and the second satellite may provide services for the same cell (e.g., have the same PCI). The first satellite may be a source satellite. The second satellite may be a target satellite. The UE may receive (enable) a first indication of an unchanged PCI mechanism or a satellite switching (e.g., satSwitchWithReSync) via a first SIB19. In response to receiving the first SIB19, the UE may start or restart a UL synchronization timer (e.g., T430). After t-Start (and before t-Service), the UE may start acquiring DL synchronization with the second satellite. At t-Service and / or after DL synchronization, the UE may stop transmitting to the first satellite. The UE may consider that the UL synchronization timer (e.g., T430) expires at t-Service. After DL synchronization, for example, in response to the expiration of the UL synchronization timer (e.g., T430), the UE may acquire a second SIB19. The second SIB19 includes satellite information after switching the serving satellite. In response to receiving the second SIB19, the UE may start a UL synchronization timer (e.g., T430), for example based on the satellite information. After DL synchronization and when the UL synchronization timer (e.g., T430) is running, for example based on the NW indication, the UE may perform a RA procedure or not perform a RA procedure. When the UL synchronization timer (e.g., T430) is running and / or when the RA procedure is performed, after DL synchronization, the UE may acquire UL synchronization with the second satellite.

[0731] For RACH-based satellite handover, the UE can trigger the RA procedure immediately after DL synchronization with the new satellite. For RACH-free satellite handover, the UE can perform UL synchronization immediately after DL synchronization with the new satellite. Fig.21 In the hard satellite handover shown in , the UE considers that the UL synchronization timer (e.g., T430) expires at t-Service and starts the UL synchronization timer (e.g., T430) immediately after acquiring the new SIB19 after DL synchronization. When the UL synchronization timer (e.g., T430) is not running, the UE cannot perform UL transmission. Before starting the UL synchronization timer (e.g., T430), the UE cannot perform the triggered RA procedure or UL synchronization. There may be a time gap between DL synchronization and performing UL synchronization. For example, Fig.23 In the soft satellite switching shown in , the time gap between DL synchronization and UL synchronization may be longer because the UE can perform DL synchronization before t-Service.

[0732] In the latest RAN2 meeting (RAN2#123bis meeting), it has been agreed that the network broadcasts the target satellite information (e.g., NTN-Config) to the UE in SIB19 in advance before the satellite switching. The UE can receive the target satellite information before the satellite switching instead of after the DL synchronization with the target satellite is performed. However, based on the current mechanism according to the RAN2 protocol, the UE still needs to wait to obtain the new SIB19 to start the UL synchronization timer (e.g., T430). Based on the expiration of the UL synchronization timer (e.g., T430), the UE cannot perform UL synchronization even if the UE has valid target satellite information. The UE may consider that the UL synchronization timer (e.g., T430) expires immediately after t-Service. In response to the expiration of the UL synchronization timer (e.g., T430), the UE considers that the UL synchronization has been lost (and obtains SIB19). In response to the UL synchronization loss, the UE clears all HARQ buffers. After DL synchronization, the UE starts T430 and considers that UL synchronization has been obtained.

[0733] Throughout the present disclosure, the target NTN information may be or be referred to as the NTN information of the target satellite. The source NTN information may be or be referred to as the NTN information of the source satellite. The target NTN information may be provided explicitly in SIB19. The target NTN information may be provided implicitly in SIB19 with a parameter for indicating one of the NTN information in SIB19. The target NTN information may be provided in a list of neighboring cells. SIB19 may (at least) contain the first NTN information, the second NTN information, and / or the third NTN information. The first NTN information may be for the source satellite. The second NTN information may be for the target satellite. The third NTN information may be for the source satellite. The first NTN information may be for the serving cell. The second NTN information may be for the serving cell, the target cell, or the neighboring cell. The third NTN information may be for the neighboring cell. The first NTN information, the second NTN information, and / or the third NTN information may be different or the same NTN information.

[0734] To solve the problem, the UE may determine whether to consider the UL synchronization timer (e.g., T430) to expire at a specific timing based on a condition. The specific timing may be the timing when the source satellite will stop providing service to the current cell. The specific timing may be a t-Service. The specific timing may be the timing when the UE starts to perform DL synchronization, perform satellite switching, and / or switch to a target satellite. The specific timing may be the timing when the UE performs DL synchronization, performs unchanged PCI switching, satellite switching, and / or switches to a target satellite.

[0735] For example, based on the conditions, the UE may not consider the UL synchronization timer (e.g., T430) to be expired during the procedure of the handover with unchanged PCI and / or the satellite handover. For example, based on the conditions, the UE may keep the UL synchronization timer (e.g., T430) running during the procedure of the handover with unchanged PCI and / or the satellite handover. The UE may not consider the UL synchronization timer to be expired during the procedure of the handover with unchanged PCI and / or the satellite handover. In response to the expiration of the UL synchronization timer, if the procedure of the handover with unchanged PCI and / or the satellite handover is ongoing, the UE may (re)start the UL synchronization timer.

[0736] Throughout the present disclosure, when the UE (determines) to implement DL synchronization (e.g., with a target satellite), a procedure for PCI unchanged handover and / or satellite handover may be initiated. When the UE receives an indication of PCI unchanged handover and / or satellite handover, the procedure for PCI unchanged handover and / or satellite handover may be initiated. When the UE receives system information containing an indication of PCI unchanged handover and / or satellite handover, the procedure for PCI unchanged handover and / or satellite handover may be initiated. When the UE acquires UL synchronization, the procedure for PCI unchanged handover and / or satellite handover may be completed. When the UE considers that UL synchronization has been obtained, the UE may acquire UL synchronization. When the UE completes the RA procedure, the procedure for PCI unchanged handover and / or satellite handover may be completed. When the UE considers that the RA procedure is successfully completed, the procedure for PCI unchanged handover and / or satellite handover may be completed. When the UE completes the RA-free procedure, the procedure for PCI unchanged handover and / or satellite handover may be completed. The PCI-invariant handover and / or satellite handover procedure may be completed when the UE (successfully) receives a PDCCH transmission addressed to the Cell Radio Network Temporary Identifier (C-RNTI) and / or the Random Access Radio Network Temporary Identifier (RA-RNTI).

[0737] The condition may be one or a combination of the following:

[0738] -Whether the NTN information of the target satellite has been received (or is received) before the unchanged PCI switch and / or satellite switch;

[0739] -Whether the NTN information of the target satellite has been received (or is received) in SIB19;

[0740] - Whether the NTN information of the target satellite has been received (or is received) together with an indication of unchanged PCI switching and / or satellite switching;

[0741] -Whether the NTN information of the target satellite has been received (or is being received) from the source satellite;

[0742] -Whether the NTN information of the target satellite is valid or available at a specific time;

[0743] - Whether two NTN information of the serving cell (e.g., one for the source satellite and one for the target satellite) have been provided (or are provided) in SIB19;

[0744] - Whether NTN information or an indication of UL synchronization is provided in SIB19; and / or

[0745] - Whether the UL synchronization timer is running based on the NTN information of the target satellite.

[0746] The UE may check the condition at a specific time. The UE may make a determination at a specific time. The UE may consider the UL synchronization timer (e.g., T430) to have expired at a specific time. Based on (at least) the condition being met, in response to (at least) the condition being met, or if (at least) the condition being met, the UE may not consider the UL synchronization timer (e.g., T430) to have expired at a specific time. Based on (at least) not meeting the condition, in response to (at least) not meeting the condition, or if (at least) the condition being met, the UE may consider the UL synchronization timer (e.g., T430) to have expired at a specific time. For example, the UE may receive SIB19 including an indication of a satellite handover and (at least) NTN information of a target satellite. The UE may initiate a procedure for a PCI-unchanged handover and / or a satellite handover. In response to the NTN information of the target satellite being available, the UE may not consider the UL synchronization timer (e.g., T430) to have expired.

[0747] To solve the problem, during the PCI unchanged handover and / or satellite handover procedure, the UE may stop the UL synchronization timer (e.g., T430) and / or (re)start the UL synchronization timer (based on the target satellite information). The UE may stop and / or (re)start the UL synchronization timer based on (at least) one or more of the following:

[0748] - after receiving system information with satSwitchWithResync (e.g., SIB19), upon receiving system information with satSwitchWithResync, or in response to receiving system information with satSwitchWithResync;

[0749] - after triggering / starting a procedure for a PCI unchanged handover and / or a satellite handover, when triggering / starting a procedure for a PCI unchanged handover and / or a satellite handover, or in response to triggering / starting a procedure for a PCI unchanged handover and / or a satellite handover;

[0750] - after t-Service, at t-Service, before t-Service, after t-Service or in response to t-Service;

[0751] - after performing DL synchronization, while performing DL synchronization, before performing DL synchronization, after performing DL synchronization or in response to performing DL synchronization;

[0752] - after, while, after or in response to stopping the UL synchronization timer;

[0753] - if (at least) or in response to target satellite information being available or having been received / acquired; and / or

[0754] - If (at least) or in response to the UL synchronization timer not being considered expired.

[0755] When the UL synchronization timer is running (e.g., based on the source satellite information), the UE may stop the UL synchronization timer. When the UL synchronization timer is not running, the UE may start the UL synchronization timer. When the UL synchronization timer is running, the UE may restart the UL synchronization timer.

[0756] Based on (at least) the condition being met, in response to (at least) the condition being met, or if (at least) the condition being met, the UE may stop the UL synchronization timer (e.g., T430) at, before, or after a specific timing. Based on (at least) not meeting the condition, in response to (at least) not meeting the condition, or if (at least) the condition being met, the UE may not stop the UL synchronization timer (e.g., T430) at, before, or after a specific timing. After stopping the UL synchronization timer (e.g., T430) or in response to stopping the UL synchronization timer, the UE may (re)start the UL synchronization timer (e.g., T430). For example, the UE may receive SIB19 including an indication of a satellite handover and (at least) NTN information of a target satellite. The UE may initiate a procedure for a PCI-unchanged handover and / or a satellite handover. The UE may perform DL synchronization with a target satellite. Before or after performing DL synchronization with a target satellite, the UE may stop the UL synchronization timer (e.g., T430). After stopping the UL synchronization timer (eg, T430), the UE may (re)start the UL synchronization timer (eg, T430) based on the NTN information of the target satellite.

[0757] The UE may stop the UL synchronization timer (e.g., T430) at the indicated timing. The indicated timing may be included in system information (e.g., SIB19). The UE may stop the UL synchronization timer (e.g., T430) immediately after t-service. After stopping the UL synchronization timer (e.g., T430), the UE may consider that UL synchronization has been lost. In response to the UL synchronization loss caused by the satellite switching, the UE determines not to clear one or more HARQ buffers. After the satellite switching, the UE may continue the transmission before the satellite switching. The transmission efficiency may be improved.

[0758] For example, the UE may receive system information (e.g., via a serving cell), wherein the system information includes at least a first NTN configuration, time information, and an indication of satellite switching. The system information may be SIB19. The indication of satellite switching may be satSwitchWithResync. The time information may be t-Service. The time information may indicate when an NTN cell (e.g., a serving cell) will stop providing services for an area currently covered by it. The first NTN configuration may be NTN-Config (for a serving cell, for a cell receiving system information). The first NTN configuration may include at least a first validity duration and a first epoch time. In response to receiving the system information, the UE may start or restart a timer based on the first NTN configuration. The timer may be a UL synchronization timer and / or a validity timer. The timer may be T430. The UE may start or restart a timer, wherein the timer value is set to the first validity duration from a subframe indicated by the free first epoch time. Based on the indication of satellite switching being included in the system information, the UE may initiate a procedure for satellite switching. The UE may stop the timer immediately after the timing indicated by the time information. After stopping the timer, the UE may consider that UL synchronization has been lost. The UE may determine whether to clear the HARQ buffer based on whether UL synchronization is lost due to satellite switching. If and / or based on (at least) UL synchronization is lost due to satellite switching, the UE may not clear the HARQ buffer. The UE may implement DL synchronization with a cell served by a (target) satellite, for example, as indicated in an indication of satellite switching. After implementing DL synchronization, the UE may start a timer based on a second NTN configuration included in the indication of satellite switching. The second NTN configuration may be NTN-Config (for the target satellite, for the cell served by the target satellite). The second NTN configuration may include at least a second validity duration and a second epoch time. The UE may start a timer, wherein the timer value is set to the second validity duration starting from the subframe indicated by the free second epoch time. After starting the timer, the UE may consider that UL synchronization has been obtained.

[0759] For example, Fig.24As shown in , based on the indication of satellite switching (e.g., satSwitchWithResync) being received in system information (e.g., SIB19), the UE may initiate a satellite switching procedure. After the timing indicated by the time information (e.g., t-Service) in the system information (e.g., SIB19), the UE may then stop the timer (e.g., T430). In response to stopping the timer (e.g., T430), the UL may consider that UL synchronization has been lost and / or stop UL transmission on the serving cell. For example, in response to stopping the timer (e.g., T430), considering that UL synchronization is lost due to satellite switching, causing UL synchronization loss due to satellite switching, and stopping UL transmission, the UE may not clear the HARQ buffer. The UE may perform DL synchronization (e.g., reading the SSB of the target satellite and / or the cell served by the target satellite). For example, after DL synchronization, the UL may start a timer (e.g., T430). In response to starting the timer (e.g., T430), the UE may consider that UL synchronization has been obtained and / or perform UL transmission on the serving cell.

[0760] In addition, upon receiving the NTN information of the target satellite, upon receiving the NTN information of the target satellite, or in response to receiving the NTN information of the target satellite, the UE may not start or restart the UL synchronization timer (e.g., T430). Upon receiving SIB19, based on the NTN information of the source satellite, the UE may then start or restart the UL synchronization timer (e.g., T430). Upon receiving SIB19, based on the NTN information of the target satellite, the UE may then not start or restart the UL synchronization timer (e.g., T430). The UE may receive the first NTN information and the second NTN information via SIB19. (In response to receiving SIB19) Based on the first NTN information but not based on the second NTN information, the UE may start or restart the UL synchronization timer (e.g., T430). (In response to receiving SIB19) the UE may not start or restart the UL synchronization timer (e.g., T430). The first NTN information is for the source satellite and / or the serving cell. The second NTN information is for the target satellite. The second NTN information is for the serving cell, the target cell, or the neighboring cell.

[0761]

[00136] To the extent possible of the methods, alternatives, concepts, examples and embodiments described above and in detail herein, the following aspects and embodiments are possible.

[0762] refer to Fig.25, utilizing this and other concepts, systems and methods of the present invention, a method 1040 for a UE in a wireless communication system includes: receiving a first indication of a satellite switch (step 1042); receiving an NTN configuration of a target satellite (step 1044); performing DL synchronization with the target satellite at an opportunity (step 1046); in response to performing DL synchronization with the target satellite, stopping an UL synchronization timer for a serving cell (step 1048); after the UL synchronization timer is stopped, starting an UL synchronization timer for a serving cell based on the NTN configuration of the target satellite (step 1050); based on the NTN configuration of the target satellite being available, not considering the UL synchronization timer expired at t-Service (step 1052); and performing an RA procedure for satellite switch while the UL synchronization timer is running (step 1054).

[0763] In various embodiments, the timing is indicated by t-Service or the timing between t-Start and t-Service.

[0764] In various embodiments, the first indication is satSwitchWithReSync.

[0765] In various embodiments, the first indication and the NTN configuration of the target satellite are received in SIB19.

[0766] Return to reference Figure 3 and 4 In one or more embodiments from the perspective of a UE in a wireless communication system, the apparatus 300 includes program code 312 stored in a memory 310 of a transmitter. The CPU 308 may execute the program code 312 to: (i) receive a first indication of a satellite handover; (ii) receive an NTN configuration of a target satellite; (iii) perform DL synchronization with the target satellite at an opportunity; (iv) in response to performing DL synchronization with the target satellite, stop an UL synchronization timer for a serving cell; (v) after the UL synchronization timer is stopped, start an UL synchronization timer for a serving cell based on the NTN configuration of the target satellite; (vi) based on the NTN configuration of the target satellite being available, do not consider the UL synchronization timer to have expired at t-Service; and (vii) perform an RA procedure for a satellite handover when the UL synchronization timer is running. In addition, the CPU 308 may execute the program code 312 to perform all of the described actions, steps, and methods described above, below, or otherwise herein.

[0767] refer to Fig.26, utilizing this and other concepts, systems and methods of the present invention, a method 1060 for a UE in a wireless communication system includes: receiving an indication of uplink synchronization loss from an upper layer (step 1062); and in response to receiving the indication of uplink synchronization loss: not performing uplink transmission on the serving cell, and determining whether to clear one or more HARQ buffers based on whether the uplink synchronization loss is caused by satellite switching (step 1064).

[0768] In various embodiments, the method further comprises: not clearing one or more HARQ buffers if the uplink synchronization loss is caused by satellite switching; and clearing one or more HARQ buffers if the uplink synchronization loss is not caused by satellite switching.

[0769] In various embodiments, the method further includes: receiving system information, wherein the system information includes at least an indication of satellite switching; initiating a satellite switching procedure based on the indication of satellite switching being included in the system information; and indicating uplink synchronization loss in response to initiating the satellite switching procedure.

[0770] In various embodiments, the indication of a satellite switch is satSwitchWithResync.

[0771] In various embodiments, the system information is SIB19.

[0772] In various embodiments, the method further comprises: starting or restarting a timer upon receiving the system information; and indicating a loss of uplink synchronization in response to expiration of the timer.

[0773] In various embodiments, the timer is T430.

[0774] In various embodiments, the upper layer is the RRC layer.

[0775] Return to reference Figure 3 and 4 In one or more embodiments from the perspective of a UE in a wireless communication system, the apparatus 300 includes program code 312 stored in a memory 310 of a transmitter. The CPU 308 may execute the program code 312 to: (i) receive an indication of uplink synchronization loss from an upper layer; and (ii) in response to receiving the indication of uplink synchronization loss: not perform uplink transmission on the serving cell, and determine whether to clear one or more HARQ buffers based on whether the uplink synchronization loss is caused by a satellite handover. In addition, the CPU 308 may execute the program code 312 to perform all of the described actions, steps, and methods described above, below, or otherwise herein.

[0776] refer to Fig. 27, utilizing this and other concepts, systems and methods of the present invention, a method 1070 for a UE in a wireless communication system includes: receiving system information, wherein the system information includes at least a first NTN configuration, time information, and an indication of a satellite switch (step 1072); in response to receiving the system information, starting or restarting a timer based on the first NTN configuration (step 1074); initiating a satellite switch procedure based on the indication of the satellite switch being included in the system information (step 1076); stopping the timer immediately after a timing indicated by the time information (step 1078); after stopping the timer, UL synchronization is considered to have been lost (step 1080); determining whether to clear one or more HARQ buffers based on whether the UL synchronization is lost due to the satellite switch (step 1082); performing DL synchronization with a cell served by a satellite indicated in the indication of the satellite switch (step 1084); after performing DL synchronization, starting a timer based on a second NTN configuration included in the indication of the satellite switch (step 1086); and after starting the timer, UL synchronization is considered to have been acquired (step 1088).

[0777] In various embodiments, the time information indicates when the NTN cell will stop providing service to the area currently covered by the NTN cell.

[0778] In various embodiments, the system information is SIB19.

[0779] In various embodiments, the time information is t-Service.

[0780] In various embodiments, the indication of a satellite switch is satSwitchWithResync.

[0781] In various embodiments, the first NTN configuration and / or the second NTN configuration is a NTN-Config.

[0782] In various embodiments, the first NTN configuration includes at least a first validity duration and a first epoch time, and / or the second NTN configuration includes at least a second validity duration and a second epoch time.

[0783] In various embodiments, the timer is T430.

[0784] In various embodiments, the UE starts or restarts the timer by a subframe indicated by a first epoch time, wherein the timer value is set to a first validity duration, and / or the UE starts the timer by a subframe indicated by a second epoch time, wherein the timer value is set to a second validity duration.

[0785] In various embodiments, the second NTN configuration is associated with a cell served by a satellite indicated in the indication of the satellite handover.

[0786] In various embodiments, the method further comprises: not clearing one or more HARQ buffers if the uplink synchronization loss is caused by satellite switching; and clearing one or more HARQ buffers if the uplink synchronization loss is not caused by satellite switching.

[0787] Return to reference Figure 3 and 4 In one or more embodiments from the perspective of a UE in a wireless communication system, the apparatus 300 includes program code 312 stored in a memory 310 of a transmitter. The CPU 308 can execute the program code 312 to: (i) receive system information, wherein the system information includes at least a first NTN configuration, time information, and an indication of satellite switching; (ii) in response to receiving the system information, start or restart a timer based on the first NTN configuration; (iii) initiate a satellite switching procedure based on the indication of satellite switching included in the system information; (iv) stop the timer immediately after the timing indicated by the time information; (v) after stopping the timer, consider that UL synchronization has been lost; (vi) determine whether to clear one or more HARQ buffers based on whether UL synchronization is lost due to satellite switching; (vii) perform DL synchronization with a cell served by a satellite indicated in the indication of satellite switching; (viii) after performing DL synchronization, start a timer based on a second NTN configuration included in the indication of satellite switching; and (ix) after starting the timer, consider that UL synchronization has been obtained. Furthermore, CPU 308 may execute program code 312 to carry out all described actions, steps, and methods described above, below, or otherwise herein.

[0788] Any combination of the concepts or teachings above or herein may be fully or partially combined or formed into new embodiments. The disclosed details and embodiments can be used to at least (but not limited to) solve the problems mentioned above and herein.

[0789] It should be noted that any of the methods, alternatives, steps, examples and embodiments presented herein may be applied independently, individually and / or in combination with multiple methods, alternatives, steps, examples and embodiments.

[0790] Various aspects of the present disclosure have been described above. It should be understood that the teachings herein can be embodied in a wide variety of forms, and any specific structure, function, or both disclosed herein are only representative. Based on the teachings herein, it should be understood by those skilled in the art that the aspects disclosed herein can be implemented independently of any other aspects, and two or more of these aspects can be combined in various ways. For example, using any number of aspects set forth herein, a device can be implemented or a method can be practiced. In addition, using other structures, functions, or structures and functions other than one or more of the aspects set forth herein or different from one or more of the aspects set forth herein, this device can be implemented or this method can be practiced. As an example of some of the above concepts, in some aspects, parallel channels can be established based on pulse repetition frequencies. In some aspects, parallel channels can be established based on pulse positions or offsets. In some aspects, parallel channels can be established based on time hopping sequences. In some aspects, parallel channels can be established based on pulse repetition frequencies, pulse positions or offsets, and time hopping sequences.

[0791] Those skilled in the art will appreciate that information and signals may be represented using any of a variety of different techniques and technologies. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltage, current, electromagnetic waves, magnetic fields or magnetic particles, optical fields or optical particles, or any combination thereof.

[0792] Those of ordinary skill in the art will further appreciate that the various illustrative logical blocks, modules, processors, components, circuits, and algorithm steps described in conjunction with the aspects disclosed herein may be implemented as electronic hardware (e.g., a digital implementation, an analog implementation, or a combination of the two, which may be designed using source decoding or some other technique), and various forms of programs or design codes with instructions (which may be referred to herein as "software" or "software modules" for convenience), or a combination of the two. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system. Those of ordinary skill in the art may implement the described functionality in different ways for each specific application, but such implementation decisions should not be interpreted as causing a deviation from the scope of the present disclosure.

[0793] In addition, the various illustrative logical blocks, modules, and circuits described in conjunction with the aspects disclosed herein may be implemented within or by an integrated circuit ("integrated circuit", IC), an access terminal, or an access point. An IC may include a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, electrical components, optical components, mechanical components, or any combination thereof designed to implement the functions described herein, and may execute code or instructions residing within the IC, outside the IC, or both. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0794] It should be understood that any specific order or hierarchy of steps in any disclosed process is an example of a sample method. It should be understood that based on design preferences, the specific order or hierarchy of steps in a process can be rearranged while remaining within the scope of the present disclosure. The accompanying method claims present elements of the various steps in a sample order, and are not intended to be limited to the specific order or hierarchy presented.

[0795] The steps of the method or algorithm described in conjunction with the various aspects disclosed herein can be implemented directly with hardware, with a software module executed by a processor, or with a combination of the two. Software modules (e.g., containing executable instructions and related data) and other data can reside in a data memory, such as a RAM memory, a flash memory, a ROM memory, an EPROM memory, an EEPROM memory, a register, a hard disk, a removable disk, a CD-ROM, or any other form of computer-readable storage medium known in the art. Sample storage media can be coupled to a machine such as a computer / processor (for convenience, the machine can be referred to as a "processor" in this article) so that the processor can read information (e.g., code) from the storage medium and write the information to the storage medium. Sample storage media can be integrated with the processor. The processor and storage medium can reside in an ASIC. The ASIC can reside in a user device. In an alternative, the processor and storage medium can reside in a user device as discrete components. In addition, in some aspects, any suitable computer program product can include a computer-readable medium, and the computer-readable medium includes code related to one or more aspects of the present disclosure. In some aspects, the computer program product can include packaging materials.

[0796] Although the present invention has been described in conjunction with various aspects and examples, it will be appreciated that the present invention is capable of further modifications. This application is intended to cover any variation, use or adaptation of the present invention that generally follows the principles of the present invention and includes such deviations from the present disclosure that occur within the known and customary practice in the art to which the present invention relates.

Claims

1. A method for a user equipment, characterized in that: include: receiving an indication of uplink synchronization loss from an upper layer; as well as In response to receiving the indication of the uplink synchronization loss: No uplink transmission is performed on the serving cell; as well as A determination is made whether to clear one or more hybrid automatic repeat request buffers based on whether the uplink synchronization loss is caused by a satellite handoff.

2. The method according to claim 1, characterized in that Further including: if at least the uplink synchronization loss is caused by the satellite handover, not clearing the one or more hybrid automatic repeat request buffers; as well as If at least the uplink synchronization loss is not caused by the satellite handover, the one or more hybrid automatic repeat request buffers are cleared.

3. The method according to claim 1, characterized in that Further including: receiving system information, wherein the system information at least includes an indication of satellite switching; a procedure for initiating a satellite handover based on said indication of said satellite handover being included in said system information; as well as Responsive to initiating the procedure for the satellite handoff, a loss of uplink synchronization is indicated.

4. The method according to claim 3, characterized in that The indication of the satellite switching is satSwitchWithResync, and / or the system information is SIB19.

5. The method according to claim 1, characterized in that Further including: Starting or restarting the timer upon receipt of the system message; and In response to expiration of the timer, loss of uplink synchronization is indicated.

6. The method according to claim 5, characterized in that The timer is T430, and / or the system information is SIB19.

7. A method for a user device, characterized in that: include: receiving system information, wherein the system information includes at least a first non-terrestrial network configuration, time information, and an indication of a satellite switch; In response to receiving the system information, starting or restarting a timer based on the first non-terrestrial network configuration; a procedure for initiating a satellite handover based on said indication of said satellite handover being included in said system information; stopping the timer immediately after the timing indicated by the time information; After stopping said timer, uplink synchronization is considered to have been lost; determining whether to clear one or more hybrid automatic repeat request buffers based on whether the uplink synchronization is lost due to a satellite handover; performing downlink synchronization with a cell served by a satellite indicated in said indication of said satellite handover; After achieving the downlink synchronization, starting the timer based on a second non-terrestrial network configuration included in the indication of the satellite handover; and After starting the timer, the uplink synchronization is considered to have been acquired.

8. The method according to claim 7, characterized in that The time information indicates when the non-terrestrial network cell will stop providing service for an area currently covered by the non-terrestrial network cell, and / or the time information is t-Service.

9. The method according to claim 7, characterized in that: The first non-terrestrial network configuration includes at least a first validity duration and a first epoch time, and / or the second non-terrestrial network configuration includes at least a second validity duration and a second epoch time.

10. The method according to claim 9, characterized in that The user equipment starts or restarts the timer by the subframe indicated by the first epoch time, wherein the timer value is set to the first validity duration, and / or the user equipment starts the timer by the subframe indicated by the second epoch time, wherein the timer value is set to the second validity duration.

11. A user equipment, characterized in that: include: Memory; as well as a processor operatively coupled to the memory, wherein the processor is configured to execute program code to: receiving an indication of uplink synchronization loss from an upper layer; In response to receiving the indication of the uplink synchronization loss: No uplink transmission is performed on the serving cell; as well as A determination is made whether to clear one or more hybrid automatic repeat request buffers based on whether the uplink synchronization loss is caused by a satellite handoff.

12. The user equipment according to claim 11, characterized in that The processor is further configured to execute the program code to: if at least the uplink synchronization loss is caused by the satellite handover, not clearing the one or more hybrid automatic repeat request buffers; as well as If at least the uplink synchronization loss is not caused by the satellite handover, the one or more hybrid automatic repeat request buffers are cleared.

13. The user equipment according to claim 11, characterized in that The processor is further configured to execute the program code to: receiving system information, wherein the system information at least includes an indication of satellite switching; a procedure for initiating a satellite handover based on said indication of said satellite handover being included in said system information; as well as Responsive to initiating the procedure for the satellite handoff, a loss of uplink synchronization is indicated.

14. The user equipment according to claim 13, characterized in that The indication of the satellite switching is satSwitchWithResync, and / or the system information is SIB19.

15. The user equipment according to claim 11, characterized in that The processor is further configured to execute the program code to: Starting or restarting the timer upon receipt of the system message; and In response to expiration of the timer, loss of uplink synchronization is indicated.

16. The user equipment according to claim 15, characterized in that The timer is T430, and / or the system information is SIB19.

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