Method for sending signal to base station and user equipment

Abstract

A method performed by a user equipment connected to a base station of a satellite communication network for transmitting a signal using an updated value of a timing advance, the user equipment determining a value of the timing advance based at least on assistance information, a measurement, a timing advance command, the method includes determining, based on a time-related parameter, a final timing advance command received at a final command time, a final measurement obtained at a final measurement time, final auxiliary information received at a final auxiliary time, a combination of at least two elements among the final measurement, the command, and the auxiliary time, the transmission time of the signal is selected among at least the following:-a target time of the transmission of the signal; and-a delay time of the signal transmission, said delay time being later than said target time; and transmitting the signal to the base station at the transmission time by using the updated value of the timing advance.

Description

Technical Field

[0001] The present disclosure relates to the field of telecommunications in non-terrestrial networks (NTNs), and more particularly to transmissions performed using satellite communication networks. Background Art

[0002] The deployment of a satellite constellation in a non-geostationary satellite orbit (or NGSO), such as in a low earth orbit (or LEO) and in a medium earth orbit (or MEO), forms a satellite communication network with coverage that varies over time and space on the surface of the earth (via satellite cells). Therefore, a user equipment (or UE) communicating through the satellite communication network performs various procedures in a wireless communication standard (such as LTE, Advanced LTE or New Radio (NR)) to obtain and / or maintain a connection to the satellite communication network over time. For example, in order to obtain initial access to a satellite cell deployed by a satellite, the user equipment may perform a random access procedure (or RACH procedure) in order to connect to the satellite communication network and be allocated resources for further transmission. For example, in order to maintain an existing connection with the satellite communication network when a coverage change occurs (e.g., due to movement of the satellite constellation), the user equipment may perform a handover procedure in order to switch its connection from a serving cell to another target cell. When the user equipment has established a connection with the satellite communication network via a satellite cell, the user equipment can notably send and receive signals to and from the satellite communication network via such satellite cell by communicating with a base station serving the satellite cell.

[0003] Such interaction with the satellite communication network thus includes data and control signals transmitted by the user equipment to the satellite communication network. In addition, when sending signals through the satellite cell, the user equipment takes into account the timing advance value to be used in the satellite cell in order to compensate for the propagation delay between the user equipment and the reference point in the satellite communication network where such signals are received.

[0004] For example, such a determination of a timing advance value occurs in a procedure for initial access based on the first message of a RACH procedure received by the base station from the user equipment (Msg1 of the RACH procedure). Later, in the same RACH procedure, the timing advance value of the user equipment in the base station is estimated by the base station and sent (Msg2 of the RACH procedure) to the UE, which uses the timing advance value to introduce a time delay when transmitting a signal through the target cell.

[0005] When a user equipment is connected to a serving cell (i.e., connected to a serving base station), the user equipment periodically updates the timing advance to be used in such a serving cell when sending signals in order to maintain uplink timing synchronization with the network. In particular, when the user equipment is connected to a serving cell, the timing advance update relies on a dual-loop mechanism. Such a dual-loop mechanism includes:

[0006] - a closed loop mechanism, which comprises the user equipment receiving an explicit timing advance command (or TAC) from the network, such timing advance command providing an updated value of the timing advance to be used by the user equipment in the serving cell. Notably, the timing advance command is received by the user equipment as a network reaction to a previous signal transmitted by the user equipment to the network, the network being able to determine the updated value of the timing advance based on such previous signal,

[0007] - An open loop mechanism comprising a self-update of the timing advance by the user equipment based on various measurements performed by the user equipment and based on assistance information received by the user equipment, in particular from the network.

[0008] In particular, the closed-loop mechanism and the open-loop mechanism run in parallel and thus provide the user equipment with various sources of information related to the timing advance update at various times. Depending on the time when such information is received by the user equipment and the timing advance correction implied by such information, the user equipment may perform an incorrect timing advance update. In fact, depending on their timing, the open-loop information and the closed-loop commands may contain redundant or contradictory information, resulting in the user equipment possibly experimenting with timing advance overcompensation or timing advance update jumps. Incorrect updates of timing advance result in loss of uplink timing synchronization. Such loss of uplink timing synchronization further results in radio link failure (or RLF), which significantly results in a waste of time, reliability and / or radio resources for both the user equipment and the satellite communication network.

[0009] Therefore, in order to maintain synchronization with the satellite communication network, a user equipment in a connected state is required to perform consistent and reliable timing advance updates based on various timing advance correction sources received according to different time patterns. Summary of the invention

[0010] The present disclosure improves upon the above situation.

[0011] A method for signaling a base station using an updated value of a timing advance, performed by a user equipment, to which the user equipment is connected, the base station corresponding to a cell supported by a non-geostationary satellite of a satellite communication network, is proposed.

[0012] The user equipment determines a value of the timing advance based on at least the following items:

[0013] - data relating to assistance information associated with an assistance time received by said user equipment,

[0014] - data relating to measurements obtained by said user equipment and associated with a measurement time,

[0015] - data relating to a timing advance command received from the network associated with a command time,

[0016] The method comprises the following steps:

[0017] Select the transmission time of the signal from at least the following:

[0018] --the target time for signal transmission, and

[0019] -- a delay time for signal transmission, the delay time being later than the target time;

[0020] sending the signal to the base station at a transmission time using an updated value of the timing advance,

[0021] The selected transmission time is selected based on a combination of at least two of the following factors:

[0022] - time-related parameters,

[0023] - data relating to a final timing advance command associated with a final command time,

[0024] - data relating to the final measurement associated with the time of the final measurement,

[0025] - data relating to final assistance information associated with a final assistance time,

[0026] - data related to the final measurement time,

[0027] - data related to the time of the final order, and

[0028] - Data related to final assist time.

[0029] The proposed method thus enables, for a user equipment connected to a satellite communication network in a cell, to use the timing advance value in the cell to send signals, more specifically uplink transmissions, as accurately as possible to a base station serving the user equipment. In particular, the method proposes to compare different but parallel sources of information capable of updating the timing advance value. Such different sources of information may be redundant or complementary information with respect to each other, depending on the time at which they provide information to the user equipment.

[0030] Therefore, by actively selecting the transmission timing of the signal, the proposed method enables the user equipment to avoid timing advance jumps, or conversely, apply over-compensation of the timing advance when sending the signal, both of which may lead to a loss of timing synchronization between the user equipment and the network side, or even to a radio link failure (or RLF) situation.

[0031] In fact, the present disclosure proposes to select the transmission time of the signal based on the following two aspects:

[0032] - data capable of quantifying the final value used as the timing advance (i.e. data relating to the final timing advance command, the final measurement and / or the final assistance information), and

[0033] - being able to determine outdated data used for quantifying such last value used as timing advance (ie data relating to the final command time, the final measurement time and / or the final assistance time).

[0034] Thus, in contrast to existing methods, the user equipment defaults to not sending a signal to the base station at the next time opportunity (or opportunity) at which the user equipment must do so (e.g., in the next time window allocated or provided to the user equipment by the network). The present disclosure enables the user equipment to take an active role in deciding when to send a signal to the base station. Furthermore, such a decision is taken by the user equipment in order to optimize the accuracy of the updated value of the timing advance to be used as the signal transmission.

[0035] The result of such selection is that the method provides the user equipment with the possibility of voluntarily (i.e., intentionally) deferring the transmission of a signal to a deferred transmission time, rather than sending the signal at the immediately upcoming time opportunity provided by the network. For example, if the user equipment determines that the data in its free use for determining the value to be used as the timing advance is outdated and / or reflects a considerable timing advance adjustment, such an intentional postponement of the transmission time of the signal can be determined by the user equipment. In such a case, the user equipment that significantly provides the timing requirements for sending the signal can decide to send the signal at a deferred transmission time relative to the target transmission time in an attempt to determine a more relevant timing advance value. For example, deferring the transmission of the signal can enable the user equipment to retrieve additional and updated information at the same time, so as to determine an updated value of the timing advance to be used for sending the signal based on such additional and updated information. Therefore, the method enables the user equipment to evaluate the information used to determine the timing advance value (as currently known to the user equipment (i.e., in its free use when it intends to send the signal)), and to inquire about the relevance of such information, such evaluation potentially affecting the timing intention of the user equipment to send the signal to the base station.

[0036] By sending a signal to the base station, it should be understood that uplink communication is performed with the base station of the satellite communication network. The signal sent by the user equipment to the base station may be a data signal (or data service). The signal sent by the user equipment to the base station may also be a control signal such as a scheduling request (or SR) or a buffer status report (or BSR). For example, such a signal may be sent to the base station in the context of a configuration authorization, a semi-configuration authorization, or a dynamic authorization. For example, in the case of a configuration authorization, the signal may be a periodic service data signal to be sent to the base station using radio resources (e.g., physical uplink shared channel resources or PUSCH resources) allocated to the user equipment UE by the network. In the case of a dynamic authorization, the signal may be an SR signal to be sent to the base station using radio resources (e.g., physical uplink control channel resources or PUCCH resources) allocated to the user equipment UE by the network in order to request PUSCH resource allocation. More generally, such a signal may be sent to the base station within a scheduling time window (or time opportunity) allocated by the network.

[0037] By connecting to a base station corresponding to a cell supported by a non-geostationary satellite of a satellite communication network, it is understood that the cell projected by the user equipment via one or more satellite beams of a satellite of the network is in an RRC_CONNECTED state, and such a cell is allocated with radio resources managed by the corresponding base station. In particular, for example, the user equipment is connected to the base station after having performed an initial access procedure (e.g., a RACH procedure) or a handover procedure from a previous cell managed by another base station to which the user equipment is connected.

[0038] By final element (e.g., final timing advance command, final assistance information, or final measurement), it is understood that the element stored in the memory of the user device will be used by the user device for the current event (such as determining the current value of the timing advance). Such a final element may, for example, be the only element at the user device's free use (e.g., a preconfigured element stored by the user device) or an element (e.g., a timing advance command, assistance information, or measurement) to which the user device receives an update. Thus, for example, in the context of a last-in-first-out (LIFO) memory, the user device has available final elements for use within its memory. Thus, given a given state of the user device's memory, such a final element is the latest element at the user device's free use. It is then possible to update such a final element so that such a final element is no longer the latest element at the user device's free use in such an updated state of its memory. For example, a final measurement refers to the measurement last obtained by the user device, for example, stored at the top of its memory in the case of a LIFO memory structure. Another measurement may occur afterwards.

[0039] By data related to auxiliary information, it should be understood that the open loop (or OL) information obtained or received by the user equipment from the network entity. Such a network entity may refer to a base station, a satellite, or any other entity on the network side. Data related to auxiliary information may refer to the content included in the system information block (or SIB) transmitted by the network that the user equipment can obtain. Data related to auxiliary information may also refer to the content of network signaling related to the location, ephemeris, attributes of satellites, satellite beams, and cells of the satellite communication network. Data related to auxiliary information may also refer to epoch time, radio resource configuration information, and cell-related information. More generally, data related to auxiliary information may refer to any content that is pre-configured, preset, set, predictable, and / or known on the network side. Based on such data related to auxiliary information, the user equipment may, for example, obtain, receive, and / or calculate the position of the satellite serving such a user equipment. Such data related to auxiliary information may be obtained by the user equipment via broadcast, multicast, and / or dedicated downlink signaling within the cell served by the network.

[0040] By data relating to final assistance information, it is to be understood that the data relating to assistance information is last received by the user equipment at the current time under consideration. In other words, the final assistance information may be understood as the most recent and updated assistance information at the free use of the user equipment at the current time. In particular, the user equipment may have determined the last value used in the timing advance (also referred to as used as the current value of the timing advance) based on such final assistance information.

[0041] By auxiliary time, it is understood that the time associated with the auxiliary information obtained by the user equipment. Such time can be expressed in terms of time units, steps, samples, time slots, etc. or according to the timestamp of the timer of the user equipment. Such auxiliary time can, for example, refer to the time when the user equipment receives the data related to the auxiliary information. Such auxiliary time can, for example, refer to the time when the user equipment can request the auxiliary information. Such auxiliary time can also refer to the time when the user equipment actually uses or calculates such data related to the auxiliary information, for example, for determining the value to be used as the timing advance. In fact, there may be a time delay between the reception time of the auxiliary information and the calculation time of such auxiliary information. The auxiliary time can then be understood as the corresponding time when the user equipment continuously receives the data related to the auxiliary information. Such auxiliary time can be set by the network according to a configured period. Such auxiliary time can correspond to a specific time window or time gap during which the data related to the auxiliary information can be provided to the user equipment or requested by the user equipment.

[0042] By final assistance time it is to be understood a time associated with the final assistance information. Such a final assistance time may also be referred to as a "last assistance time". Thus, such a final assistance time may for example refer to a time at which the user equipment received data relating to the final assistance information. Such a final assistance time may also refer to a time at which the user equipment actually used or calculated such data relating to the final assistance information, for example for determining a current value to be used as a timing advance. In other words, the final assistance time is the latest time at which the user equipment has received data relating to the assistance information.

[0043] By data relating to measurements, it is understood that the open-loop (or OL) information obtained, calculated and / or measured by the user equipment. Such data relating to measurements may be radio signal measurements performed by the user equipment using positioning techniques. Such data relating to measurements may also be data collected by the user equipment from sensors integrated into the user equipment. Such data relating to measurements can significantly enable the user equipment to estimate the position of the user equipment. By data relating to final measurements, it is understood that the data relating to the measurements last performed or obtained by the user equipment at the current time under consideration. In other words, the final measurement may be understood as the most recent and updated measurement at the user equipment's free disposal at the current time. In particular, the user equipment may have determined the last value used in the timing advance based on such final measurements.

[0044] By measurement time, it is understood that the time associated with the measurement performed or obtained by the user equipment. Such time can be expressed in terms of time units, steps, samples, time slots, etc. or according to the timestamp of a timer of the user equipment. Such measurement time may, for example, refer to the time at which the user equipment can obtain data related to the measurement. Such auxiliary time may also refer to the time at which such data related to the measurement can be actually used or calculated by the user equipment, for example, for determining the value to be used as a timing advance. In practice, there may be a time delay between the time at which the measurement is performed or obtained and the time of calculation or processing of such measurement for determining the value to be used as a timing advance. The measurement time may correspond significantly to a measurement time gap configured by the network, during which the user equipment can perform the measurement. The measurement time may also be a time set by the user equipment for performing the measurement.

[0045] By final measurement time it is to be understood a time associated with a final measurement performed or obtained by the user equipment. Such a final measurement time may also be referred to as a "last measurement time". Thus, such a final measurement time may, for example, refer to a time at which the user equipment received data relating to the final measurement. Such a final auxiliary time may also refer to a time at which such data relating to the final measurement was actually used or calculated by the user equipment, for example, for determining a current value to be used as a timing advance. In other words, the final measurement time is the latest time at which the user equipment has obtained or processed data relating to the measurement.

[0046] By data relating to a timing advance command, it is understood that data is contained in a timing advance command (or TAC) signal transmitted by the network. Such a TAC signal is specifically sent to the user equipment via the MAC-CE as a dedicated downlink signal. Such data relating to a timing advance command may correspond to the timing advance command 6-bit value contained in the MAC-CE TAC signal. Therefore, such data relating to a timing advance command may relate to closed loop (or CL) information of a source providing a timing advance adjustment from the network to the user equipment. Such data relating to a timing advance command may be a timing advance adjustment value between 0 and 63 units.

[0047] By command time, it should be understood that the time associated with the data related to the timing advance command. Such time can be expressed in time units, steps, samples, time slots, etc. or according to the timestamp of the timer of the user equipment. Such command time may, for example, refer to the time when the user equipment receives the data related to the TAC signal. Such command time can also refer to the time when such data related to the timing advance command can actually be used, calculated or applied by the user equipment, for example, for determining the value to be used as the timing advance. In fact, there may be a time delay between the reception time of the timing advance command signal and the application of the content of such a timing advance command signal for determining the value to be used as the timing advance. For example, in the case of closed-loop adjustment, such a time delay can be six time slots. The command time is determined by the network. The command time can also depend on the user equipment sending an uplink signal to the base station. For example, the network is indeed able to transmit a timing advance correction via a TAC signal based on the timing information of such an uplink signal. In other words, as long as the user equipment sends an uplink signal, the base station can transmit a timing advance command at the command time.

[0048] By final command time, it is to be understood the time associated with the final timing advance command signal received by the user equipment. Such a final command time may also be referred to as a "last command time". Thus, such a final command time may, for example, refer to the time at which the user equipment receives data relating to the final timing advance command. Such a final auxiliary time may also refer to the time at which such data relating to the final timing advance command (e.g., a timing advance adjustment value contained in a TAC) is actually used or applied by the user equipment, for example, for determining a current value used as a timing advance or for sending a signal using such a current value used as a timing advance. In other words, the final command time is the most recent time at which the user equipment has received or applied data relating to the timing advance command.

[0049] By target transmission time of a signal it is to be understood the immediately next time opportunity (or time window) given to the user equipment for sending the signal S. Such a target transmission time may in particular be the immediately upcoming time opportunity allocated by the network, for example in the context of a configured or semi-configured grant. Such a target transmission time may also refer to the immediately upcoming time opportunity provided by the network for sending a control signal (such as a BSR or SR signal). More generally, the target transmission time of a signal refers to the nearest upcoming time opportunity relative to the current time at which the user equipment sends a signal to the base station.

[0050] By the deferred transmission time of the signal, it should be understood that the next time opportunity (or time window) given to the user equipment for sending the signal S. Such a deferred transmission time may be, for example, an upcoming time window configured by the network in the context of a configuration or semi-configuration authorization. Such a deferred transmission time may also refer to a time opportunity allocated by the network for sending a control signal (e.g., a BSR or SR signal) to the base station. In particular, the deferred transmission time is understood to be a slightly later time opportunity relative to the target transmission time. In other words, such a deferred transmission time is a delayed time opportunity for the user equipment to send a signal to the base station. Such a deferred transmission time may be one or more time slots later than the target transmission time.

[0051] By selecting the transmission time of the signal, it should be understood that a specific time window (also referred to as a specific time opportunity or time chance) configured by the network for sending a signal to the base station is selected. In other words, the timing of the user equipment's selection of the signal transmission is a deliberate choice (or decision). In particular, by selecting the transmission time as a delay time on the target transmission time, the user equipment deliberately decides to postpone the transmission of the signal despite having an earlier time opportunity (i.e., the target transmission time) available to do so.

[0052] By selecting the selected transmission time based on a combination of at least two elements, it should be understood that such selection can be performed with significant consideration of one or more constraints (or criteria). In other words, the user equipment considers multiple elements in order to decide the transmission time to be selected. Such constraints may include time-related parameters. Time-related parameters are understood to be time-related constraints to be considered by the user equipment for sending signals. Time-related parameters may, for example, refer to defined and specific time opportunities allocated by the network in which the transmission time can be selected. For example, in the context of a configured or semi-configured authorization, a plurality of configured time windows may be allocated to the user equipment, during which the user equipment may send signals to the base station. Such a configured time window may significantly include at least a target transmission time and a deferred transmission time. In the context of a dynamic authorization, a plurality of configured time windows may be allocated to the user equipment, during which the user equipment may send a control signal (e.g., send an SR) to the base station, so as to, for example, obtain additional resources to send data signals. Time-related parameters may also refer to, for example, the timing requirements to be met by the user equipment in the context of the delay requirements defined in the service level agreement (or SLA) of the service served by the user equipment. In other words, the transmission time of the signal may be selected to meet the delay requirements. The time-related parameter may also refer to a time threshold, such as a time threshold set, preconfigured, configured or predetermined by the user equipment or the network. Such a time threshold may depend significantly on the current time at which the user equipment selects the transmission time. Such a time threshold may enable an outdated check to be performed on the current information possessed by the user equipment for sending a signal to the base station, such information being, for example, a timing advance command, auxiliary information and / or measurement that has been obtained by the user equipment. In other words, the time threshold may enable the user equipment to distinguish information that is considered relevant and received at a sufficiently close time from information that is susceptible to outdatedness and is therefore not relevant, significantly in order to determine an updated value for the timing advance. Specifically, the user equipment may use the time threshold to identify whether the user equipment may need to obtain updated information in order to determine an updated value for the timing advance.

[0053] The transmission time may also be selected based on data related to the final measurement time, the final command time, and / or the final assistance time. In other words, the user equipment may select the transmission taking into account the final measurement time, the final command time, and / or the final assistance time, significantly possibly delaying the transmission of the signal. In other words, the user equipment may select the transmission time based on the time at which the user equipment has obtained or used the most recent and up-to-date information. For example, if the final measurement time, the final command time, and / or the final assistance time are considered out-of-date, the user equipment may select the transmission time as the delayed transmission time.

[0054] The transmission time may also be selected based on data related to the final timing advance command, the final measurement, and / or the final assistance information. In other words, the user equipment may select the transmission time based on the content of the most recent and latest information obtained or used by the user equipment. For example, if the final timing advance command, the final measurement, and / or the final assistance information reflects a large timing advance adjustment for which the user equipment may postpone the transmission of a signal for further information, the user equipment may select the transmission time as the postponed transmission time.

[0055] By the updated value of the timing advance, it should be understood that the value to be determined by the user equipment and used to send a signal to the base station to compensate for the propagation delay between the user equipment UE and a predefined network reference point, which may be located, for example, at a base station BS managing a cell or at a satellite SAT supporting a cell, or any reference point between these two points. In particular, such an updated value of the timing advance may be determined before the transmission time of the signal, so that the user equipment may use such an updated value of the timing advance to send a signal to the base station. Such an updated timing advance amount may be determined by the user equipment to be equal to the current value used as the timing advance amount, that is, the value that the user equipment has determined or used at the current time. The current value used as the timing advance may, for example, have been determined at a previous time (before the current time) and used to send a previous signal. For example, the current value used as the timing advance may have been used to send the last signal sent by the user equipment to the base station. Such a current value to be used as the timing advance may be determined significantly based on the final timing advance command, the final measurement and the final auxiliary information. The updated value to be used as the timing advance may also be different from the current value used as the timing advance. If the information possessed by the user equipment is considered out of date at the current time and for example updated information is available, such updated value to be used as the timing advance may differ significantly from the current value used as the timing advance.

[0056] According to one embodiment of the present disclosure, the method further includes:

[0057] A supporting signal different from the signal is transmitted to the base station, the supporting signal being sent at a supporting time dependent on a target transmission time of the signal.

[0058] Thus, the user equipment may be able to send another signal different from the signal to be sent at the transmission time in order to prepare for the latter's transmission. In particular, such a support signal may be sent to the network as a request for updated auxiliary information or updated measurements relative to the final auxiliary information or the final measurement, respectively. Such a support signal may also be sent to the network as a request for an updated timing advance command relative to the final timing advance command. In addition, the support signal may be sent in the context of a configuration authorization, a semi-configuration authorization or a dynamic authorization. In particular, the user equipment may send a support signal to the base station even in the case of a configuration authorization, wherein the user equipment has pre-allocated physical uplink shared channel (or PUSCH) resources. The user equipment may, for example, decide to postpone the transmission of the signal to the postponed transmission time, and send a support signal in advance to request updated information for determining an updated value to be used as a timing advance.

[0059] By a support signal it is understood that the user equipment performs an uplink transmission to the base station. Notably, such a support signal is sent before the signal is sent. Such a support signal may notably be a control signal, such as a BSR or SR signal.

[0060] By such a support signal depending on the target transmission time, it should be understood that the user equipment can decide the timing of the support time depending on the upcoming time opportunity to transmit a signal to the base station. The support time can be before or after the target transmission time.

[0061] According to an embodiment of the present disclosure, the user equipment determines the value of the timing advance using data related to the assistance information and data related to the measurement providing the value of the self-correction parameter,

[0062] And the transmission of the supporting signal is also based on at least one of the following standards:

[0063] - the first time gap between the final command time and the current time exceeds a preconfigured first gap threshold, or

[0064] - Final command time before final assist time, and:

[0065] -- the second time gap between the final auxiliary time and / or the final measurement time and the current time exceeds a preconfigured second gap threshold, or

[0066] - A value of a self-correction parameter determined based on data related to the final assistance information and / or the final measurement exceeds a preconfigured self-correction threshold.

[0067] The proposed method thus enables sending a support signal to a base station in order to request updated information for determining an updated value to be used as the timing advance.

[0068] By the first time gap between the final command time and the current time exceeding the preconfigured first gap threshold, it should be understood that if the final timing advance command at the time of free use of the user equipment has become outdated at the current time, a support signal may be sent. Therefore, the user equipment may need an updated timing advance command and therefore send a support signal to the end.

[0069] By preconfigured first gap threshold, it is to be understood that the time gap is configured by the user equipment or the network. Such preconfigured first gap threshold significantly quantifies the obsolescence of the closed-loop information. For example, if the time gap between the command time and the current time exceeds the preconfigured first gap threshold, the timing advance command associated with such command time is considered to be outdated content for determining the updated value to be used as the timing advance.

[0070] By the final command time being before the final assistance time and the second time gap between the final assistance time and / or the final measurement time and the current time exceeding the preconfigured second gap threshold, it should be understood that if the latest information obtained by the user equipment is open-loop information and if the open-loop information has become outdated at the current time, a support signal may be sent. Therefore, the user equipment may need updated closed-loop information and / or updated open-loop information, and therefore may send a support signal to the end.

[0071] By a preconfigured second gap threshold, a time gap configured by the user equipment or the network is to be understood. Such a preconfigured second gap threshold significantly quantifies the obsolescence of the open-loop information. For example, if the time gap between the auxiliary time and / or the measurement time and the current time exceeds the preconfigured second gap threshold, the auxiliary information associated with such auxiliary time and / or the measurement associated with such measurement time is considered to be outdated content for determining an updated value to be used as a timing advance. The preconfigured second gap threshold may be different from or equal to the preconfigured first gap threshold.

[0072] By the final command time being before the final assistance time and the second time gap between the final assistance time and / or the final measurement time and the value of the self-correction parameter determined based on the data related to the final assistance information and / or the final measurement exceeding the preconfigured self-correction threshold, it should be understood that if the latest information obtained by the user equipment is open-loop information and if the open-loop information reflects the required significant (or large) timing advance adjustment (or correction), a support signal can be sent, and significant is understood to exceed the self-correction parameter. Therefore, the user equipment may need updated closed-loop information and / or updated open-loop information to further quantify such required timing advance adjustment, and therefore a support signal can be sent to the end.

[0073] By self-correction parameters it is to be understood that the timing advance correction (or adjustment) value provided by the assistance information obtained from the network and / or the measurements performed by the user equipment, both of which lead to a self-adjustment of the timing advance by the user equipment. Thus, such self-correction parameters may enable the user equipment to perform larger adjustments to the timing advance value than the correction parameters provided by the network via, for example, a timing advance command (since the correction parameters provided by the network via, for example, a timing advance command are size-limited). Such self-correction parameters quantize the open-loop information (or the open-loop correction of the timing advance).

[0074] By preconfigured self-correction threshold, it is understood that a threshold is configured by the network or user equipment. Such a threshold may be expressed in terms of the number of timing advance correction units. Such a preconfigured self-correction threshold may significantly reflect how significant (or how much) the open-loop correction is. For example, if the self-correction parameter is below the preconfigured self-correction threshold, the open-loop correction may be considered negligible, whereas if the self-correction parameter is above the preconfigured self-correction threshold, the open-loop correction may be considered significant.

[0075] According to an embodiment of the present disclosure, the time-related parameter is related to the validity time of data used to determine the value of the timing advance, and the transmission of the support signal is also based on the following criteria:

[0076] - Any of the final command time, the final measurement time, and the final assistance time is before the valid time.

[0077] Therefore, if any part of the latest information is considered outdated when the user equipment is free to use it, the user equipment can actively send a supporting signal to the base station, outdated being understood as before the validity time.

[0078] By effective time, it should be understood that the time slot before the current time. Such effective time can be set or configured by the user equipment or the network. Such effective time can vary significantly according to the current time. For example, the effectiveness can be a time slot with two time slot gaps from the current time. Specifically, comparing the final command time with the effective time can be equivalent to comparing the first time gap between the final command time and the current time with a preconfigured first gap threshold. In particular, comparing the final auxiliary time and / or the final measurement time with the effective time can be equivalent to comparing the second time gap between the final auxiliary time and / or the final measurement time and the current time with a preconfigured second gap threshold. In particular, in the case of equal preconfigured first gap threshold and second gap threshold, such a gap threshold corresponds to the time gap between the current time and the effective time.

[0079] According to an embodiment of the present disclosure, a support signal is transmitted using a support value of the timing advance, wherein the support value of the timing advance is determined based on a combination of at least two elements among at least the following:

[0080] - time-related parameters,

[0081] - data relating to the final timing advance command received,

[0082] - data related to the final measurement performed,

[0083] - data related to the final assistance information received,

[0084] - data related to the final measurement time,

[0085] - data related to the time of the final order, and

[0086] - Data related to final assist time.

[0087] Therefore, a support signal can be transmitted using a support value for the timing advance so as to at least partially anticipate a timing advance adjustment to be applied to a signal sent to a base station. In fact, by applying the support value for the timing advance when sending a support signal based on the most recent information when the user equipment is in free use, the user equipment reduces the time difference to be compensated by the timing advance when sending an uplink transmission to the base station. Therefore, when indicating a timing advance correction to be applied to the user equipment, the updated open-loop or closed-loop information (if any) received thereafter takes into account such a support value for the timing advance. In particular, such a support value for the timing advance can be determined based on the most recent information when the user equipment is in free use at the current time. In other words, the support value for the timing advance can correspond to the current value of the timing advance last determined by the user equipment.

[0088] According to an embodiment of the present disclosure, the support signal includes at least one of the following elements:

[0089] - uplink reference signals, such as sounding reference signals,

[0090] - control signals,

[0091] - Cache status reporting, and

[0092] - Scheduling request.

[0093] Thus, the support signal to be sent to the base station may be sent in the context of a configured grant, a semi-configured grant or a dynamic grant. Thus, such a signal may be sent using physical uplink shared channel resources (or PUSCH) or physical uplink control channel (or PUCCH) resources. In particular, in contrast to prior art approaches, the user equipment may decide to send the support signal even in the case of a configured grant, where the user equipment already has dedicated PUSCH resources for sending the signal.

[0094] According to an embodiment of the present disclosure, if:

[0095] - data relating to updated assistance information is predicted to be associated with an updated assistance time between the target transmission time and the deferred transmission time, and / or

[0096] - the data relating to the updated measurement are determined to be associated with an updated measurement time between the target transmission time and the deferred transmission time,

[0097] The transmission time is then selected as the delayed transmission time.

[0098] Therefore, if the user equipment determines that postponing the transmission of the signal can enable the user equipment to obtain updated information in order to determine the updated value to be used as the timing advance, the user equipment can intentionally decide to postpone the transmission of the signal by selecting the transmission time as the postponed transmission time relative to the target transmission time. In particular, if it is predicted or determined that updated open-loop information is received, obtained or applied between the target transmission time and the postponed transmission time, the user equipment postpones the transmission of the signal. Therefore, compared with only using the information currently at the free use of the user equipment (in particular, the final timing advance command, the final auxiliary information and the final measurement), the user equipment intentionally decides to give up the time opportunity to send the signal at the target transmission time in order to wait for the updated information that is used to determine the more relevant updated value to be used as the timing advance.

[0099] By updated assistance information, it should be understood that the assistance information is received after the final assistance information. Compared to the final assistance information, such updated assistance information will be significantly more accurate open loop information for determining the updated value of the timing advance to be used as the transmitted signal. Such updated assistance information is not freely available to the user equipment at the current time (i.e., unknown). The user equipment may significantly predict or determine that such updated assistance information can be obtained by the user equipment at an updated assistance time. By updated assistance time, it should be understood that the time is later than the current time associated with the updated assistance information. Such updated assistance time may be the time at which the user equipment will receive, obtain, apply or utilize the updated assistance information.

[0100] By the data relating to the updated assistance information being predicted to be associated with an updated assistance time, it will be appreciated that the user equipment may be able to estimate the immediately upcoming assistance time at which the updated assistance information will be at the free use of the user equipment. In particular, such prediction is possible in the context of system information blocks (or SIBs) and other network information that are broadcast periodically by the network at configured times or according to a configuration known to the user equipment. Such an updated assistance time is predictable based on previous assistance information previously received at a previous assistance time.

[0101] By data relating to updated measurements, it should be understood that measurements are performed after the final measurement. Such measurements will be significantly more accurate open-loop information for determining an updated value to be used as a timing advance for transmitting a signal than the final measurement. The user equipment does not have such updated measurements at the current time. The user equipment can significantly determine that such updated measurements can be obtained, performed or applied by the user equipment at an updated measurement time. By updated measurement time, it should be understood that a time later than the current time associated with the updated measurement by the user equipment should be understood. If the user equipment has hardware capabilities for determining measurement times, such updated measurement times can be significantly anticipated when the user equipment selects such updated measurement times. Such updated measurement times can also be configured by the network as measurement gaps provided by the network in which the user equipment can perform updated measurements.

[0102] According to an embodiment of the present disclosure, data related to a timing advance command providing a value of a correction parameter is used by a user equipment to determine a value of the timing advance,

[0103] And if:

[0104] - the gap between the final command time and the current time is below a preconfigured first threshold, and

[0105] - a value of a correction parameter determined based on data related to the final timing advance command exceeds a preconfigured correction threshold, and

[0106] - data relating to updated assistance information are predicted to be associated with an updated assistance time later than a final assistance time and later than a current time, the updated assistance time being between a target transmission time and a postponed transmission time, and / or data relating to updated measurements are determined to be associated with an updated measurement time later than a final measurement time and later than a current time, the updated measurement time being between a target time and a postponed time,

[0107] The transmission time is then selected as the postponed time.

[0108] Thus, even if the final timing advance command is not considered outdated information, the user equipment may intentionally decide to forgo the nearest time opportunity provided by the network for sending a signal and postpone the sending of the signal. Indeed, if the final timing advance command reflects a significant timing advance adjustment (significant is understood here as a timing advance correction sent by the network exceeding a preconfigured correction threshold) and if upcoming open-loop information may potentially be received, the user equipment may decide to postpone the sending of the signal in order to further determine, confirm or quantify such closed-loop correction. Indeed, in such a context, if the user equipment determines or predicts that updated auxiliary information and / or updated measurements are associated with (i.e., to be received, obtained or applied) after the target transmission time, the user equipment may decide to wait for such upcoming information by postponing the transmission of the signal. In such a way, the proposed method is able to prevent potential overcompensation of timing advance due to overlapping and concurrent sources of timing advance corrections (i.e., open-loop and closed-loop).

[0109] According to an embodiment of the present disclosure, determination of an updated value of the timing advance for transmitting a signal is performed based at least on the updated assistance information associated with the updated assistance time and / or the updated measurement associated with the updated measurement time.

[0110] Thus, notably when such open loop information is available to the user equipment before the transmission time, the updated value of the timing advance to be determined by the user equipment and to be used for sending a signal to the base station may depend on the updated open loop information. Thus, the proposed method enables the user equipment to determine a more relevant updated value to be used as the timing advance than an updated value of the timing advance determined only on information that the user equipment has free use at the current time.

[0111] According to an embodiment of the present disclosure, when determining a value of a timing advance, the user equipment updates a value of a timing error parameter related to error estimation, and the method further includes:

[0112] If the transmission time is selected as the target time, the timing error parameter is updated.

[0113] Therefore, the user equipment can evaluate the accuracy of the timing advance implementation used when determining the value of the timing advance used to send a signal to the base station. In particular, when the user equipment decides to send a signal at the next upcoming time opportunity provided by the network, the user equipment can quantify the timing error parameter so that the user knows the accuracy of its calculation process. In fact, the user equipment can decide to send a signal at the target transmission time because the user equipment determines that it does not need to update the information and the final timing advance command, the final auxiliary information and the final measurement remain related to the update value determined to be used as the timing advance. In such a case, the user equipment has no reason to intentionally postpone the transmission of the signal and decides to perform the transmission of the signal as quickly as possible (i.e., at the target transmission time). In such a case, the timing error parameter can be updated to increase the accuracy of the timing advance implementation. However, despite the need for updated closed-loop and / or open-loop information, for example, due to the delay requirement of sending the signal (for example, due to the delay requirement, the user equipment cannot postpone its transmission to the postponed transmission time), the user equipment can decide to send the signal at the target transmission time. In such a case, the timing error parameter may be updated so as to reduce the accuracy of the timing advance achieved, since the user equipment knows that by relying only on the final information, the updated value to be used as the timing advance may not be accurate.

[0114] By a timing error parameter, it is to be understood a counter value (e.g., a cumulative counter value), or a percentage that quantifies the error (or equivalently, the accuracy) of a timing advance value achieved by a user equipment. For example, if the user equipment knows that the value to be used as the timing advance determined by the user equipment is inaccurate, such a timing error parameter may be increased. For example, if the user equipment knows that the value to be used as the timing advance determined by the user equipment is accurate, such a timing error parameter may be decreased.

[0115] According to an embodiment of the present disclosure, the data related to the timing advance command provides the value of the correction parameter used by the user equipment to determine the value of the timing advance,

[0116] And the updating of the timing error parameter includes if:

[0117] - the gap between the final command time and the current time is below a preconfigured first threshold, and

[0118] The value of the correction parameter determined based on the data related to the final timing advance command exceeds a preconfigured correction threshold, and

[0119] data relating to updated assistance information is predicted to be associated with an updated assistance time later than a final assistance time, the updated assistance time being later than the postponed time, and / or data relating to updated measurements is predicted to be associated with an updated measurement time later than a final measurement time, the updated measurement time being later than the postponed time,

[0120] Then increase the value of the timing error parameter.

[0121] Thus, in the event that the final closed-loop information reflects a significant timing advance correction (i.e., the closed-loop correction exceeds a preconfigured correction threshold), but the user equipment has no upcoming opportunity to obtain updated open-loop information to further quantify, determine, or confirm such closed-loop correction before sending a signal, the user equipment may increase the timing error parameter. Such a situation is significant if the updated open-loop information is predicted to be obtained, received, or applied after a postponed transmission time. In such a situation, the user equipment knows that, although updated information is needed, such updated information will not be obtained in time to determine an updated value of the timing advance to be used for sending the signal. Therefore, the updated value to be used as the timing advance will not be as accurate as by relying on updated open-loop information, resulting in an increase in the timing error parameter.

[0122] By correction parameter it is to be understood a timing advance correction (or adjustment) value provided by the network, in particular via a timing advance command. Such a threshold may be expressed in terms of the number of timing advance correction units. Such a correction parameter may be defined notably by the timing advance value contained in the MAC-CE timing advance command and may therefore have a defined correction size. The user equipment notably relies on such correction parameter to determine the timing advance value. Such a correction parameter quantifies the closed loop information (or closed loop correction of the timing advance).

[0123] By preconfigured correction gap threshold, it should be understood that the threshold is configured by the network or user equipment. Such a threshold can significantly reflect how significant (or obvious) the closed-loop correction is. For example, if the correction parameter is below the preconfigured correction threshold, the closed-loop correction can be considered negligible, while if the correction parameter is above the preconfigured correction threshold, the closed-loop correction can be considered significant.

[0124] According to an embodiment of the present disclosure, data related to the assistance information providing the value of the self-correction parameter and data related to the measurement are used by the user equipment to determine the value of the timing advance, and data related to the timing advance command providing the value of the correction parameter is used by the user equipment to determine the value of the timing advance.

[0125] And the updating of the timing error parameters includes:

[0126] - if the gap between the final command time and the current time is below a preconfigured alternative first threshold,

[0127] and a value of a correction parameter determined based on data related to the final timing advance command is below a preconfigured alternative correction threshold,

[0128] - or if the final command time is before either the final auxiliary time or the final measurement time,

[0129] and a value of a self-correction parameter determined based on the data relating to the final assistance information and / or based on the data relating to the final measurement is below a preconfigured alternative self-correction threshold,

[0130] and the gap between the final auxiliary time and / or the final measured time and the current time is below a preconfigured alternative second threshold,

[0131] Then reduce the value of the timing error parameter.

[0132] Thus, in the case where the final closed-loop information or the final open-loop information reflects a negligible timing advance correction (i.e., a correction below a preconfigured alternative correction or self-correction threshold), the user equipment may reduce the timing error parameter, and further such final information is not considered outdated (i.e., the final assistance time, the final command time and / or the final measurement time are below a preconfigured alternative first threshold and / or second threshold). In such a case, the updated value determined by the user equipment to be used as the timing advance may correspond to the current value of the timing advance determined based on the final information when the user equipment is free to use. Thus, the user equipment determines that the updated value of the timing advance determined in dependence on such final information is accurate and reduces the timing error parameter.

[0133] In particular, the preconfigured alternative first threshold or second threshold and the preconfigured alternative correction or self-correction threshold may be equal to or different from the preconfigured first threshold or second threshold and the preconfigured correction or self-correction threshold, respectively. Such thresholds may be significantly different if the update of the timing error parameter is normalized or adjusted so that the timing error parameter does not take negative values. Such thresholds may also differ depending on the level of accuracy of the timing advance calculation process performed by the user equipment: for example, reducing the timing advance error may require more reliability than increasing the timing advance error. In the remainder of the present disclosure and for simplicity, the preconfigured alternative first (or second) threshold and the preconfigured first (or second) threshold are considered equal, and the term "preconfigured first (or second) threshold" is used. Similarly, the preconfigured alternative correction (or self-correction) threshold and the preconfigured correction (or self-correction) threshold are considered equal, and the term "preconfigured correction (or self-correction) threshold" is used.

[0134] According to an embodiment of the present disclosure, the time-related parameter is associated with a transmission deadline, and the transmission time of the signal is selected to be before the transmission deadline.

[0135] Therefore, the user equipment may select the transmission time under the constraints of the latency requirements to be met by the user equipment (eg, in the context of the SLA of the service served by the user equipment).

[0136] By transmission deadline it is to be understood the latest time slot in which a signal must be sent to the base station. In such a case, the time-related parameter may be a time slot or time interval reflecting the level of deferral of a signal to be sent to the base station.

[0137] According to an embodiment of the present disclosure, the method further includes: if a third time gap between the final measurement time and the final assistance time exceeds a preconfigured third gap threshold, performing an updated measurement at an updated measurement time.

[0138] Therefore, the proposed method also ensures that the open loop information used by the user equipment to determine the update value to be used as the timing advance is significantly coherent between the timing of the auxiliary information obtained by the user equipment from the network and the timing of the measurement performed by the user equipment. For example, when determining the propagation delay between the satellite and the user equipment, the user equipment may need data related to the position of the user equipment on the one hand and the position of the satellite on the other hand. The former can be obtained via measurement, while the latter can be obtained via auxiliary information. Such information still has to be time-coherent (more precisely, their time gap (called the third time gap) may not exceed a preconfigured third gap threshold) so that the comparison of such user equipment position and satellite position data is meaningful. Such a preconfigured third gap threshold can be configured by the user equipment or the network. For example, such a preconfigured third gap threshold can correspond to one time slot gap. For example, such a preconfigured third gap threshold can be less than both the preconfigured first gap threshold and the second gap threshold.

[0139] In another aspect of the present disclosure, there is also provided a user equipment, the user equipment being configured to send a signal to a base station using an updated value of a timing advance, the user equipment being connected to the base station, the base station corresponding to a cell supported by a non-geostationary orbit satellite of a satellite communication network,

[0140] The user equipment can determine the value of the timing advance based on at least the following:

[0141] - data relating to assistance information associated with an assistance time received by a user equipment,

[0142] - data relating to measurements obtained by the user equipment and associated with the measurement time,

[0143] - data relating to a timing advance command received from the network associated with a command time,

[0144] The user device comprises a processor and a non-transitory computer-readable medium including instructions stored thereon, the instructions, when executed by the processor, configuring the user device to:

[0145] Select the signal transmission time from the following options:

[0146] --the target time for signal transmission, and

[0147] -- a delay time later than the target time,

[0148] The updated value of the timing advance is used to signal the base station at the transmission time,

[0149] The selected transmission time is selected based on a combination of at least two of the following factors:

[0150] - time-related parameters,

[0151] - data relating to a final timing advance command associated with a final command time,

[0152] - data relating to the final measurement associated with the time of the final measurement,

[0153] - data relating to final assistance information associated with a final assistance time,

[0154] - data related to the final measurement time,

[0155] - data related to the time of the final order, and

[0156] - Data related to final assist time.

[0157] In another aspect of the present disclosure, a computer program product is also proposed, wherein the computer program product includes program instruction codes stored on a computer-readable medium for executing the above method.

[0158] In another aspect of the present disclosure, a non-transitory computer-readable medium storing instructions of a computer program is also proposed, wherein the computer program enables the program to implement the above method when executed by a processor.

[0159] Additional features, details and advantages will be shown in the following detailed description and in the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0160] Figure 1 The overall architecture of the satellite communication network in the embodiment of the present disclosure is illustrated.

[0161] Figure 2 The overall architecture of the satellite communication network in the embodiment of the present disclosure is illustrated.

[0162] Figure 3 is a flow chart showing steps for sending a signal to a satellite communication network.

[0163] Figure 4 is a flow chart showing steps for sending a signal to a satellite communication network.

[0164] Figure 5 A timeline of signals received and transmitted by a user equipment in an embodiment of the present disclosure is illustrated.

[0165] Figure 6 A timeline of signals received and transmitted by a user equipment in an embodiment of the present disclosure is illustrated.

[0166] Figure 7 A timeline of signals received and transmitted by a user equipment in an embodiment of the present disclosure is illustrated.

[0167] Figure 8 The overall architecture of a user equipment in an embodiment of the present disclosure is schematically shown. DETAILED DESCRIPTION

[0168] Now refer to the attached Figure 1 and Figure 2 . Figure 1 and Figure 2 The overall architecture of the same part of a satellite communication network NW at two different times t1 and t2, t2 being later than t1, according to a possible implementation of the present disclosure is illustrated. The present disclosure is not limited to any particular standard, however, for simplicity, the present disclosure will be described in the context of the New Radio (NR) standard.

[0169] The satellite communication network NW comprises at least one satellite SAT. Such a satellite SAT is deployed in a non-geostationary satellite orbit (or NGSO) such as a low earth orbit (LEO) or a medium earth orbit (MEO). The satellite SAT thus has an altitude between 300 km and 30,000 km relative to the earth's surface.

[0170] The satellite SAT is linked to at least one ground station or gateway node (not in Figure 1 and Figure 2 (as shown above), so that the satellite SAT is linked to the core network via the ground station.

[0171] The satellite SAT deploys at least one satellite beam. The satellite beam is configured in a specific frequency band so that the satellite can send and receive data via the satellite beam according to the radio resources allocated in the frequency band configured for the satellite beam. These radio resources can be shared according to a frequency division scheme (e.g., frequency division multiplexing (FDM) or orthogonal frequency division multiplexing (OFDM)) or by a time division scheme (e.g., time division multiplexing (TDM)) or a code division scheme (code division multiplexing (CDM)), polarization multiplexing, or a combination thereof.

[0172] The allocation of radio resources of the satellite beams is implemented by at least one base station BS (also called gNodeB or gNB). Each base station BS manages the radio resources of one or more satellite beams. The base station BS can be located on the satellite SAT so that the distance between the base station BS and the satellite SAT is considered to be zero. The base station BS can also be located on the satellite SAT. Figure 1 and Figure 2 The distance between the base station BS and the satellite SAT is not zero and may vary as the satellite SAT moves according to the non-geostationary satellite orbit. This variation in the distance between the base station BS and the satellite SAT due to the movement of the satellite SAT is Figure 1 and Figure 2 The above is particularly illustrated by the different distances d1 and d2, respectively.

[0173] The satellite SAT projects a footprint on the surface of the Earth via one or more satellite beams deployed by the satellite SAT, also referred to as the service area of ​​the coverage area of ​​the satellite SAT. Such a coverage area deploys one or more cells, each of which is formed by deploying one or more satellite beams. The radio resources allocated in each cell are managed by the base station BS. In other words, being covered by a cell is equivalent to being allocated radio resources by the corresponding base station BS.

[0174] Reference Figure 1 and Figure 2 , the satellite communication network NW shown comprises a satellite SAT showing a satellite beam. The satellite SAT projects a unique cell corresponding to the base station BS (in Figure 1 and Figure 2 In other possible embodiments, the satellite communication network NW may include a plurality of satellites SAT and / or the satellite SAT may include a plurality of satellite beams and / or project one or more cells.

[0175] In the context of the present disclosure, the satellite SAT of the satellite communication network NW is considered to have a non-geostationary orbit. In other words, the satellite SAT moves relative to the surface of the earth according to predefined ephemeris and according to predefined satellite constellation dynamics and network topology. Such ephemeris is known in the core network, for example. Therefore, the movement and continuous position of the satellite SAT throughout the time are known to the core network and, by extension, can be accessed by any network entity. For example, a network entity may refer to a satellite SAT, a base station BS, or a ground station. A network entity does not usually refer to a user equipment UE or a device served by the network NW. For example, data related to the movement and continuous position of the satellite SAT throughout the time can be exchanged between different network entities of the satellite communication network NW using inter-satellite links (ISLs) and / or feeder link communications. The movement of the satellite SAT is illustrated as an arrow SAT MOV, which indicates that the satellite SAT moves from the left to the right in a portion of the satellite communication network NW.

[0176] In particular, the movement of the satellites SAT according to the predictable satellite constellation dynamics results in the movement of the coverage area projected by the satellites SAT on the Earth's surface in a predictable manner. Therefore, each area (e.g., the Earth's surface) covered by cells deployed by the satellite communication network NW will experience coverage changes due to the non-geostationary nature of the satellite orbits. For a considered area covered by the satellite communication network NW, the changes in coverage will occur according to a predictable timeline and under predictable coverage conditions, which significantly depend on the architecture of the satellite communication network NW. For example, referring to Figure 1 and Figure 2 , the grey area representing the cells deployed by the satellite SAT moves between time t1 and t2.

[0177] In particular, such an architecture of the satellite communication network NW may include the fixed or steerable nature of the satellite beam of the satellite SAT. In fact, in the case where the satellite SAT is equipped with a fixed satellite beam, the satellite beam does not move relative to the satellite SAT. In particular, such a fixed satellite beam has a fixed orientation relative to the satellite SAT when the satellite beam is deployed. Therefore, the cell deployed by the satellite SAT moves in a progressive manner according to the movement of the satellite SAT. In the case where the satellite SAT is equipped with a steerable (or mobile) satellite beam, the satellite beam is steered as the satellite SAT moves following its predefined orbital trajectory, such beam steering being adjusted to the movement of the satellite SAT so that the cell deployed by such a satellite beam remains approximately on the same coverage area during a predetermined time. As a result, the cell (or at least the central part of the cell) can be considered to be immovable in the coverage area for a predetermined time. Such time depends significantly on the extent to which the steerable characteristics of the satellite beam enable the latter to compensate for the movement of the satellite SAT, until, for example, a given elevation angle between the satellite beam and the surface of the Earth is reached, and above this given elevation angle, the satellite beam is turned off and replaced by another satellite beam (not in Figure 1 and 2 Thus, the duration and condition of coverage under the considered cell deployed by the satellite SAT is a function of such architecture of the satellite communication network NW. In the context of the present disclosure, fixed or steerable satellite beams may be considered for the satellite SAT. Figure 1 and Figure 2 An example of a satellite SAT with a fixed satellite beam is illustrated.

[0178] At least one user equipment UE is considered to be connected to the satellite communication network NW. The user equipment UE may generally refer to a device whose connection may be served by the satellite communication network NW for the Internet of Things (or IoT). The user equipment UE may be located on the surface of the Earth. The user equipment UE may also be far from the surface of the Earth (for example, in the case of an aircraft in flight).

[0179] In the context of this disclosure, the user equipment UE is covered by at least one cell of the satellite communication network NW and may be allocated radio resources by the corresponding base station BS. In another embodiment, the user equipment UE may be covered by a plurality of different cells corresponding to a plurality of respective base stations.

[0180] The user equipment UE is considered to be in RRC_CONNECTED state via a cell corresponding to a base station BS of the network NW. In other words, the user equipment UE has been connected to the considered cell by performing an initial access procedure (eg a random access procedure or RACH) or a handover procedure.

[0181] Therefore, the user equipment UE can use the radio resources allocated by the base station BS to send and receive signals. Such signals can be exchanged with the base station BS. Such signals can also be exchanged with other devices via direct (or side link) communication without relaying such signals via the base station BS.

[0182] In the connected state, the user equipment UE can send control signaling and / or service data to the base station BS. For example, the user equipment UE can perform data transmission, send a scheduling request (or SR) and / or send a buffer status report (or BSR) to the base station BS. The user equipment UE can perform uplink transmission.

[0183] The traffic data and signaling to be sent by the user equipment UE may be intended to serve various services, especially in the context of enhanced mobile broadband (eMBB), massive machine type communication (mMTC) or ultra-reliable and low latency communication (URLLC) use cases. Such services served by the user equipment UE have quality of service (or QoS) requirements (notably, regarding reliability and latency). Therefore, the user equipment UE may send buffered traffic data and / or various signals (such as SR and BSR signals) to the base station BS before sending the traffic data.

[0184] A scheduling request (or SR) and / or a buffer status report (or BSR) may be sent by the user equipment UE in the context that data to be sent is available in a buffer of the user equipment UE. The SR and / or BSR may also be sent in the context of a periodic report to be performed by the user equipment UE. More generally, the SR and / or BSR may be sent in the context of a number of events requiring the user equipment UE to send information to the network NW or to request resource allocation from the network NW.

[0185] The user equipment UE may send such a signal according to a specific time window (also referred to as a "transmission opportunity" or "transmission opportunity") arranged by the network NW. For example, the network NW may configure a specific defined timing opportunity for performing data transmission but also for sending an SR or BSR signal to the base station BS. Such a time window may be defined by a configuration grant, a semi-configuration grant or a dynamic grant for performing transmissions to the base station BS. Therefore, in the case of a configuration grant, for example in the context of periodic service data to be sent, the network NW allocates radio resources (e.g., physical uplink shared channel resources or PUSCH resources) to the user equipment UE for sending a BSR message to the base station BS and / or for performing uplink data transmission based on the scheduled time window. The network NW may also allocate radio resources (e.g., physical uplink control channel resources or PUCCH resources) to the user equipment UE for sending an SR message to the base station BS within a specific allocated time window in order to request PUSCH resource allocation. In case of dynamic grant, the network NW may allocate radio resources (eg PUCCH resources) representing one or more time opportunities at which the user equipment UE may, for example, send a BSR signal in order to request one dedicated time opportunity to send a data signal.

[0186] In the connected state, the user equipment UE can also receive signals from at least the base station BS. For example, the user equipment UE can receive system information (or SI), control information, network commands and / or data signals. The user equipment UE can receive downlink transmissions.

[0187] For example, the user equipment UE may receive a system information block (or SIB) from various network entities (such as a base station of the network NW) via one or more cells covering the location of the user equipment UE. The user equipment UE may receive network information related to satellite ephemeris, epoch time, radio resource configuration information, cell-related information, etc. Such information received from the network NW via a cell covering the location of the user equipment UE is referred to as auxiliary information. Such auxiliary information may be specifically received by the user equipment UE, for example as a unicast signal transmitted from the base station BS to the user equipment UE via dedicated downlink signaling. Such auxiliary information may also be public information sent to multiple devices including the user equipment UE via a broadcast or multicast channel, for example as a multicast or broadcast signal. For example, intra-cell auxiliary information may be received by all devices covered by the same cell.

[0188] Such assistance information may be sent by the network NW according to a preconfigured periodicity. The content of such assistance information and the preconfigured periodicity of its transmission may be implemented by a network entity (e.g. a base station BS) via reconfiguration. The user equipment UE then has a preconfigured periodic opportunity to retrieve such assistance information. Such a periodic opportunity is called an assistance time A.N The user equipment UE may also request assistance information within pre-configured opportunities for assistance information requests.

[0189] The user equipment UE may also receive instructions (or commands) and adjustment information from the base station BS. In particular, the user equipment UE may receive a timing advance command (or TAC) (also referred to as MAC-CE TAC (or MAC control element timing advance command)) via the medium access control (or MAC) layer.

[0190] Such a TAC signal may be received by the user equipment UE from the base station BS. Although the time for providing such a TAC command is entirely up to the decision of the network NW in order to enable the base station BS to estimate the true timing error of the uplink synchronization, it is convenient for the BS to send such a command signal after one or more uplink transmissions are performed by the user equipment UE to the base station BS. The time at which the user equipment UE may receive such a TAC signal is referred to as the command time C N .

[0191] Such a TAC signal notably includes a command value related to the timing advance to be used by the user equipment UE to send signals to the base station BS. Such a command value adopts 6 bits in the MAC-CE and can therefore vary between 0 and 63 characters. The timing advance used by the user equipment UE to send signals to the base station BS will be described in detail further in the description.

[0192] The user equipment UE may also perform measurements, such as measurements of the position of the user equipment UE. For this purpose, the user equipment UE may be equipped with a global navigation satellite system (or GNSS). The user equipment UE may also use positioning techniques based on radio signal measurements (via the network NW), or hybrid techniques (combining radio measurements with information from integrated sensors), or any other techniques to obtain data related to its own position.

[0193] Such measurements may be performed simultaneously with the new radio (or NR) signaling. In such a case, the user equipment UE may have specific hardware capable of using the measurement and signaling functions simultaneously. Such measurements may also be performed at a preconfigured time window (or time opportunity) set by the network NW. In such a case, the network NW may provide a specific measurement time window, during which the user equipment UE does not receive a signal from the network NW and has the opportunity to perform measurements. If the user equipment UE hardware is not capable of using the measurement and signaling functions simultaneously, a network preconfigured measurement time for performing the measurements may be set. The measurements may also be performed according to the implementation of the user equipment UE, depending on its requirements and its hardware capabilities. The time at which such measurements may be performed by the user equipment UE depending on the user equipment UE or preconfigured by the network NW is referred to as the measurement time M.N .

[0194] Thus, when a user equipment UE is connected to the satellite communication network NW via a cell corresponding to a base station BS, the user equipment UE is able to exchange control and traffic data signals with the base station BS and perform various measurements. However, such exchanges and measurements may be performed conditional on specific timing requirements. For example, the timing for sending signals depends significantly on:

[0195] - preconfigured transmission opportunities set by the network NW,

[0196] - Latency requirements set by a Service Level Specification (or SLS) (more generally, by a Service Level Agreement (or SLA)) to be guaranteed by a User Equipment UE performing a transmission (eg a data transmission).

[0197] For example, the timing for receiving a signal depends significantly on:

[0198] - preconfigured and / or reconfigured periods set by the network NW for sending assistance information,

[0199] - Command time C when the base station BS sends a TAC signal to the user equipment UE N ,

[0200] - A preconfigured request time opportunity for the User Equipment UE to request assistance information and more generally for sending a signal to the Base Station BS.

[0201] For example, the measurement time M used to perform the measurement N depending on:

[0202] -Hardware capabilities of the user equipment UE,

[0203] - A preconfigured measurement time window set by the network NW.

[0204] In addition, in order to send a signal to the base station BS via the cell, the user equipment UE needs to adjust the timing of the signal to be sent, and such a time adjustment is called the timing advance TA to be used in the cell. From the perspective of the user equipment UE, the timing advance TA in the cell refers to the time difference between the transmission time of the uplink communication from the user equipment UE through the cell and the reception of the downlink communication through the same cell. The timing advance TA is variable and depends on the propagation delay between the user equipment UE and a predefined network reference point (such as the base station BS that manages the cell or the satellite SAT that supports the cell or any reference point between these two points). In addition, each user equipment UE is appropriate depending on its position relative to the network reference point considered. The timing advance TA is intended to compensate for such propagation delay: the user equipment UE, after obtaining such a time advance, advances the time of its uplink transmission through the cell by the amount of time corresponding to the timing advance TA. When each user equipment UE under the coverage of a given cell advances the time of its own uplink transmission through the cell by the amount of time corresponding to its own timing advance TA, it ensures that all uplink transmissions arrive at the network side (i.e., the network reference point as defined) at the time corresponding to the radio resources to which these transmissions are allocated. Furthermore, at such a reference point, both uplink and downlink transmissions are synchronized.

[0205] The reference point is set to a parameter of the network NW. For example, the network reference point is set at the base station BS, which is, for example, the case of a terrestrial communication network. In this case, a timing advance TA specific to the user equipment UE is implemented at each user equipment UE to ensure that all uplink transmissions from such UE arrive at the base station BS in a synchronous manner with respect to the base station BS, and that the uplink transmission and the downlink transmission are time-aligned at the base station BS. In another example, the network reference point may be located at the satellite SAT. In this case, a timing advance TA specific to the user equipment UE is implemented at each user equipment UE to ensure that all uplink transmissions from such UE arrive at the satellite SAT in a synchronous manner with respect to the base station BS, and that the uplink transmission and the downlink transmission are time-aligned at the satellite SAT. In another example, the network reference point may be located anywhere on the feeder link linking the satellite SAT and its gateway. Such a network reference point is predefined for a given cell and is fixed with respect to its distance (some may be zero) to the corresponding base station BS, cell, and gateway.

[0206] In the context of the present disclosure (notably in the appended Figure 1 and Figure 2), the user equipment UE is connected to the satellite communication network NW via a cell corresponding to a base station BS, such base station BS serving the user equipment UE. Therefore, the user equipment UE has performed at least one timing advance synchronization, for example during an initial access procedure via a random access procedure (or a RACH procedure). Therefore, the user equipment UE has received at least one timing advance command (or TAC) from the base station BS, for example during the initial access procedure via a TAC random access response (or TAC-RAR), such timing advance command having provided an initial value related to the timing advance TA to be used by the user equipment UE to connect to the network NW via the base station BS. Such an initial access procedure using the initial value related to the timing advance TA to be used by the user equipment to connect to the base station BS may, for example, have been performed at a time before time t1.

[0207] Once the user equipment UE is connected to the network NW, the user equipment UE regularly requires updates of the timing advance when sending signals to the base stations BS in order to maintain uplink timing synchronization with such base stations BS. In practice, due to the movement of the satellite SAT, the movement of the satellite beam and the possible movement of the user equipment UE, the user equipment UE is subject to the same timing advance as (e.g. Figure 1 and Figure 2 The propagation delay between the network reference points considered (set at the base station BS on the UE) may vary over time. Therefore, the value to be used as the timing advance TA by the user equipment UE when sending a signal to the base station BS also varies, and an updated value of the timing advance TA used in the cell corresponding to the base station BS is needed.

[0208] In order to update the timing advance TA value to be used when sending signals to the base station BS in the RRC_CONNECTED state, the user equipment UE may rely on two different sources of timing advance adjustment:

[0209] - Closed loop information, which includes a timing advance command (TAC) signal received from a base station BS via MAC-CE. Such a TAC signal is sent by the user equipment UE at time C i Received, where i corresponds to an integer. Typically, the user equipment UE applies the received TAC value at a predefined time after having received the TAC signal (e.g., applying the TAC signal received in time slot n starting from time slot n+6). From this perspective, in the context of the present disclosure, the timing advance command is associated with the command time C i Associated, command time C i It may be the time when the user equipment UE receives the TAC command, or the time when the user equipment UE applies the TAC command, or more generally, the command time C i The timing advance command TAC may refer to a time related to or associated with the receipt of the timing advance command TAC. The remainder of this disclosure will refer to “at the command time Ci Receive TAC signal at the time of C i May refer to the time (or time slot) when the user equipment UE actually uses or applies the TAC command. As described above, the TAC signal is received based on the uplink signal previously sent from the user equipment UE to the base station BS. In NR, each TAC signal received via MAC-CE has a fixed size of 8 bits, and 6 bits correspond to the timing advance command. Therefore, as long as the user equipment UE transmits an uplink signal to the base station BS, the user equipment UE is able to receive an updated TAC signal. The correction of the timing advance TA value is limited to the length of 6 bits in each TAC signal, which limits the amount of timing advance adjustment that the user equipment UE can perform on the timing advance TA. In particular, the timing advance adjustment that may be provided by the TAC signal is between 0 and 63 units,

[0210] - Open loop information, which includes self-adjustment of the timing advance value calculated by the user equipment UE based on assistance information received from the network NW and measurements performed by the user equipment UE. The user equipment UE at the assistance time A i Receive assistance information, where i corresponds to an integer. The measurement is performed by the user equipment UE at the measurement time M i Execute, where i corresponds to an integer. Such an auxiliary time A i and measurement time M i It may also refer to the time at which the user equipment UE applies the assistance information and the measurement, respectively. More generally, the assistance time A i and measurement time M i A and B may refer to times related to or associated with obtaining assistance information and measurements, respectively. The remainder of this disclosure will refer to “at assistance time A”. i Obtain auxiliary information" and "At the measurement time M i Get measurement", however, such time A i and M i It may refer to the time (or time slot) at which the user equipment UE actually uses or applies the auxiliary information and measurements. As described above, part of the open-loop information may be retrieved by the user equipment UE according to a preconfigured period, within a specific preconfigured auxiliary time window and / or depending on the hardware capabilities of the user equipment UE. In particular, the user equipment UE is able to use the open-loop information to perform a larger adjustment of the timing advance TA value relative to the adjustment using the closed-loop information. In fact, as described above, the closed-loop information has a limited information size defined by the 6-bit size of each TAC signal, while the open-loop information enables the user equipment UE to perform self-adjustment, thereby achieving a more flexible adjustment of the timing advance TA value relative to the TAC-related adjustment.

[0211] More generally, the timing advance TA value applied by the user equipment UE in the cell corresponding to the base station BS can be expressed as:

[0212] TA=(N TA +N TA,UE-specific +N TA,common +N TA,offset )×T c in:

[0213] -TA is the updated timing advance value (e.g., in milliseconds (ms) or nanoseconds (ns)),

[0214] -N TA is the command value of the timing advance TA provided by the closed loop,

[0215] -N TA,UE-specific is a self-adjustment value determined by the user equipment UE based on an open loop,

[0216] -N TA,common is a preconfigured value set by the network NW according to the propagation delay between the satellite SAT and the considered network reference point,

[0217] -N TA,offset is the offset value assigned to the user equipment UE,

[0218] -T c is the chip time. Such a chip time may be fixed or configurable. For example, in the 3GPP NR standard, this value is fixed at 0.509 nanoseconds (ns).

[0219] Thus, when in RRC_CONNECTED mode, the user equipment UE has at each considered time a current value of the timing advance TA. Such current value of the timing advance TA may for example correspond to a last timing advance TA value calculated by the user equipment UE at or before such considered time. Such current value of the timing advance TA may for example correspond to a last timing advance TA value used by the user equipment UE when sending signals to the base station BS. Such current value of the timing advance TA at such considered time depends significantly on:

[0220] - based on the last (or final) command time C received by the user equipment UE from the base station BS and N The last (or final) command value N determined by the at least one last TAC signal associated TA,N ,

[0221] - The last (or final) self-adjusted value N determined based on TA,UE-specific,N :

[0222] - last (or final) assistance information received by the user equipment UE from one or more network entities (e.g. a base station BS) and associated with a last (or final) assistance time AN,

[0223] --Performed by the user equipment UE and related to the final measurement time M N The last (or final) measurement associated with it.

[0224] Command value N TA,i It can also be called a correction parameter or closed-loop correction. Self-adjustment value N TA,UE-specific,i It can also be called self-correction parameter or open-loop correction.

[0225] In particular, such a final self-adjusting value N TA,UE-specific,N Depends on the location of the user equipment UE and the distance d of the user equipment UE relative to the satellite SAT UE，1 ,d UE，2 The final self-adjusting value N TA,UE-specific,N It can be updated periodically by the user equipment UE based on the auxiliary information according to a configured period, for example, when the network NW sends a system information block (or SIB) in the cell. Such a period can usually be on the order of a few seconds. Such a final self-adjustment value N TA,UE-specific,N It may also be updated by the user equipment UE based on GNSS measurements performed by the user equipment UE, the frequency and measurement time of which M i It may depend on the user equipment UE capabilities and implementation.

[0226] The preconfigured value N used by the user equipment UE to determine the value of the timing advance TA at the time considered TA,common depends significantly on the distance between the satellite SAT and the network reference point. In particular, if the network reference point is set at the satellite, then such a preconfigured value N TA,common Such a preconfigured value N may be updated by the user equipment UE, for example, when the network NW sends a system information block (or SIB) in the cell according to a configured period, or when the user equipment UE receives a radio resource control parameter. TA,common .

[0227] For example, see Figure 1 , it is considered that at time t1 the user equipment UE has determined a current value used as timing advance TA in the cell. Such current value used as timing advance TA may depend significantly on the distance d between the position of the user equipment UE at time t1 corresponding to the position of the cell within the network NW and the position of the satellite SAT at time t1 UE，1 and satellite SAT and network reference points (with Figure 1 Assuming such a situation of a satellite communication network NW, the current value used as the timing advance TA in the cell at time t1 may have been received by the user equipment UE based on the last command time C received by the user equipment UE before time t1.N , Auxiliary time A N and measurement time M N The open-loop and closed-loop information obtained at

[0228] The user equipment UE may not know the actual real-time position of the satellite SAT at a given time (such as time t1) with high accuracy. The user equipment UE can calculate the approximate position of the satellite SAT at a given time, for example, by relying on auxiliary information and / or a predefined equation representing the trajectory of the satellite SAT. For example, the user equipment UE can use the satellite SAT position (for example, sent by the network NW through the SIB) of a previous time (for example, the ephemeris at the associated epoch time) and a predefined formula to estimate the satellite SAT position at a given time. With the position of the satellite SAT, the current disclosure can refer to the approximate position of the satellite SAT calculated by the user equipment UE, or if the exact position of the satellite SAT is known by other means, it can refer to the exact position of the satellite SAT, or it can refer to a position related to or representing the actual position of the satellite SAT at the current or previous time or obtained from the actual position of the satellite SAT.

[0229] Reference Figure 2 , the situation of such a part of the satellite communication network NW at time t2 has evolved relative to time t1. In fact, the satellite SAT has moved according to the preconfigured satellite ephemeris SAT MOV, thereby changing the distance d of the user equipment UE relative to the satellite SAT at time t1. UE，1 Modify to the new distance d UE，2 , and the distance d1 between the satellite SAT and the network reference point at time t1 is modified to a new distance d2. In another embodiment, the situation of such a part of the satellite communication network NW may also change at time t2 due to the movement of the user equipment UE within the fixed position of the cell between time t1 and t2. In such a case, the distance d1 between the user equipment UE and the satellite SAT is modified to a new distance d2. UE，1 . Depending on how the reference point is defined, the distance d1 between the satellite SAT and the network reference point may or may not change between time t1 and t2. Taking into account such an evolution of the situation of the satellite communication network NW between time t1 and t2, the current value of the timing advance TA used in the cell at time t1 has potentially become inaccurate for sending signals to the base station BS at time t2. In fact, such a current value of the timing advance TA may no longer be able to compensate for the propagation delay between the user equipment UE and the network reference point at time t2, and therefore, if the user equipment UE sends a signal S at time t2 using the current value of the timing advance TA, there is a risk that such a signal S fails to arrive at the network side (e.g., the base station BS) at a time corresponding to the resources to which such a signal S is allocated.

[0230] If the inaccurate value of the timing advance TA cannot compensate the propagation delay between the user equipment UE and the network reference point to a considerable extent (for example, if the current value of the timing advance determined for time t1 is reused at a later time t2), a timing desynchronization between the uplink signals expected from the user equipment UE and other UE devices occurs on the network side, resulting in inter-user interference. In addition, the uplink signals actually received by the network side from the user equipment UE and the downlink signals transmitted by the network side may also occur. As a result, the link quality between the user equipment UE and the network NW is reduced, and if a plurality of uplink and / or downlink messages cannot be decoded, the user equipment UE may consider that the connection to the network NW is lost, which is called a radio link failure (or RLF). If RLF occurs, there is a service interruption, and in addition, the user equipment UE may initiate another random access procedure (or RACH procedure) in order to try to reconnect to the network NW. Therefore, such repetition of the random access procedure wastes a lot of time and resources of both the user equipment UE and the network side.

[0231] In this case, the present disclosure proposes a method performed by the user equipment UE for sending a signal S to the base station BS using an updated value of the timing advance TA.

[0232] In the context of this disclosure, Figure 8 The above schematically shows a schematic diagram of the overall architecture of a user equipment UE capable of executing such a method.

[0233] The user equipment UE comprises at least input communication means INP, a storage memory unit MEM-UE, a processing unit PROC-UE and output communication means OUT. In one embodiment, the input communication means INP and the output communication means OUT may be combined in a single communication unit.

[0234] The input communication device INP enables the user equipment UE to receive signals from other entities including network entities (such as base stations of a satellite communication network NW). It can optionally enable the user equipment UE to receive signals from other devices and user equipment, for example via side link communication. To this end, the input communication device 1 may include a receiver, such as a radio frequency antenna, a demultiplexer, etc. In particular, the input communication device 1 may include new radio (NR) hardware.

[0235] The storage memory unit MEM-UE enables the user equipment UE to store information received via the input communication means INP and / or processed by the processing unit PROC-UE. In particular, the storage memory unit MEM-UE may include a non-volatile memory unit MEM1, a volatile memory unit MEM2 (e.g., a random access memory) and a buffer unit BUF. The buffer unit BUF may, for example, store service data to be sent by the user equipment UE.

[0236] The processing unit PROC-UE enables the user equipment UE to process information received via the input communication means INP and information stored by the storage memory unit MEM-UE, resulting in sending signals, calculating values, deciding actions, etc. In particular, the processing unit PROC-UE of the user equipment UE is capable of executing the method proposed in the present disclosure and Figure 3 and Figure 4 . To this end, the processing unit PROC-UE may, for example, include a general processing unit PU1, a decision unit PU2, a timing advance calculation unit PU3 and a transmission unit PU4. The general processing unit PU1 may be capable of preprocessing and / or processing data received via the input communication device INP and stored in the storage memory unit MEM-UE. For example, the general processing unit PU1 may timestamp the received and / or stored information. The general processing unit PU1 may manage the overall functions and applications of the user equipment UE. The decision unit PU2 may be capable of triggering any decision taken by the user equipment UE, such as transmitting a signal, calculating a timing advance value, performing a random access procedure, postponing any of the procedures, etc. The timing advance calculation unit PU3 is capable of determining an update value to be used as a timing advance TA in the cell. The transmission unit PU4 is capable of transmitting signals S, S', such signals S, S' are, for example, data signals or control signals. Such a transmission unit PU4 notably transmits signals S, S' via an output communication device OUT, which is capable of sending signals S, S' transmitted by the transmission unit PU4. Such a transmission unit PU4 may perform transmissions such as uplink transmissions or optionally sidelink unicast, multicast and / or broadcast transmissions.The output communication device OUT may comprise a transmitter, a multiplexer or the like.

[0237] Now refer to Figure 3 . Figure 3 1 represents a step for sending a signal S to a base station BS using an updated value of a timing advance TA according to the present disclosure.

[0238] In step S1, the user equipment UE intends to send a signal S to the base station BS via a cell corresponding to the base station BS connected to the user equipment UE. Such an intention to send the signal S may be triggered by various events on the user equipment UE side. For example, the intention to send the signal S may be triggered by the availability of data buffered in the buffer unit BUF of the user equipment UE, a timer of the user equipment UE, a periodic report to be sent to the network NW, a requirement for the network NW to retrieve information or allocate resources, etc. Such a step S1 may occur at a time T, which is also referred to as the current time T.

[0239] In anticipation of a signal S to be sent, the user equipment UE may collect information to be used for sending such a signal S at step S2. In particular, the user equipment UE may obtain at step S2 data relating to the current value of the timing advance in the cell. Such data relating to the current value of the timing advance in the cell may notably include: - last received (or last applied) closed loop information about the current time T: the user equipment UE may take into account at step S2 the last received (or last applied) closed loop information received from the base station BS relating to the corresponding last command time C N The last (or final) TAC signal associated with it,

[0240] -Last obtained open loop information about the current time T: The user equipment UE may take into account in step S2 the last auxiliary time A retrieved from one or more base stations N In step S2, the user equipment UE may also process the last (or final) auxiliary information signal associated with the last measurement time M N The associated last (or final) measurement, - is used to determine the pre-configured parameters required for the timing advance value.

[0241] In particular, in step S2, the user equipment UE may determine whether such data about the current value of the timing advance in the cell are sufficient and relevant, taking into account the current time T, in order to obtain a value to be used as the timing advance TA in the cell when sending the signal S. To this end, the user equipment UE may take into account the last command time C N , Auxiliary time A N and measurement time M N For example, the user equipment UE can compare the last auxiliary time A N With the last measurement time M N Compare to evaluate the consistency of the final open-loop information. Final auxiliary time A N and the last measurement time M N The time gap between the last command time C and the last command time C can be significantly compared with a preconfigured threshold (also referred to as a preconfigured third threshold). The user equipment UE can also compare the last command time C N , Auxiliary time A N and measurement time M NThe comparison is made relative to the current time T. The user equipment UE may also use the last command time C N , Auxiliary time A N and measurement time M N The predefined threshold time T known to the user equipment UE ths (or predefined threshold ths) for comparison. Such a predefined threshold time T ths It may also be referred to as validity time or threshold time. Such a time comparison may notably be intended to determine whether data relating to the current value of the timing advance TA in the cell should be considered to be significantly outdated with respect to the current time T. In particular, if the last command time C N , Auxiliary time A N and measurement time M N Any one of them is valid at time T ths Before (or equivalently, if the last command time C N , Auxiliary time A N and measurement time M N If the time gap between any one of the time advances in the cell and the current time T exceeds the predefined threshold ths), the user equipment UE may determine that the current value of the timing advance in the cell is outdated relative to the current time T. The effective time T may be predefined in a dynamic manner ths , so that the effective time T ths can vary with the current time T. For example, if the current time T is defined as a given time slot, the effective time T can be ths Defined as the time slot that is ten slots before a given time slot.

[0242] In an embodiment, the final command time C N Compare with the preconfigured first threshold. If the final command time C N Before the preconfigured first threshold, the final command time C N The associated final timing advance command is then considered outdated closed-loop information. Similarly, the final auxiliary time A N and / or final measurement time M N Compare with the preconfigured second threshold. If the final auxiliary time A N and / or final measurement time M N Before the preconfigured second threshold, the final auxiliary time A N and / or final measurement time M N The associated final assistance information and / or final measurement is then considered as outdated open-loop information. In the remainder of this disclosure, the preconfigured first and second thresholds are considered equal and are referred to as the validity time T thsHowever, in another embodiment, notably in case of different time tolerances between closed-loop information and open-loop information, such thresholds may be different.

[0243] In step S2, the user equipment UE may also process the final closed-loop information and the final open-loop information to estimate a required size, value or ratio of the timing advance adjustment relative to the current value of the timing advance TA. To this end, the user equipment UE may estimate the value of the timing advance adjustment relative to the current value of the timing advance TA used in the cell and compare such value of the timing advance adjustment with the threshold adjustment value N ths Specifically, if the estimated required value of the timing advance adjustment exceeds the threshold adjustment value N ths , the user equipment UE determines that when it is expected to send the signal S, a significant timing advance correction is required for the current value of the timing advance.

[0244] In particular, such timing advance adjustment includes a timing advance adjustment indicated by final closed-loop information (also referred to as final closed-loop correction) or a correction parameter. Such timing advance adjustment also includes a timing advance adjustment indicated by final open-loop information (also referred to as final open-loop correction) or a self-correction parameter. Then, the timing advance adjustment is equal to the threshold adjustment value N. ths The comparison may include comparing the correction parameter to a preconfigured correction threshold and comparing the self-correction parameter to a preconfigured self-correction threshold, respectively. Such preconfigured correction and self-correction thresholds are intended to quantify how significant the open-loop and closed-loop corrections are, respectively. Therefore, if the correction parameter contained in the final timing advance command exceeds the preconfigured correction threshold, it means that the final timing advance command indicates a significant (or large) timing advance adjustment. Similarly, if the self-correction parameter obtained from the final measurement and / or final auxiliary information exceeds the preconfigured self-correction threshold, it means that the final auxiliary information and / or final measurement indicates a significant (or large) timing advance adjustment. In the remainder of the present disclosure and for simplicity, the timing advance adjustment will be compared to the threshold adjustment value N ths A comparison is made, but it should be understood that such a comparison can be performed on the scale of open-loop and closed-loop information.

[0245] Therefore, during step S2, the user equipment UE determines whether the user equipment UE needs updated information for determining an updated value of the timing advance TA in the cell for sending the signal S. In other words, during step S2, the user equipment UE determines whether the signal S can be transmitted without causing timing desynchronization on the network side based on the information stored in the storage memory unit MEM-UE enabling determination of the current value of the timing advance.

[0246] If the user equipment UE determines that it is not necessary to obtain updated closed-loop and / or open-loop information in order to calculate an updated value of the timing advance TA for sending the signal S in the cell, the user equipment UE then determines, in step S2, a transmission time T corresponding to a time opportunity configured by the network NW for sending the signal S. snd In particular, the user equipment UE may select the transmission time T snd The next opportunity to send the signal S relative to the current time T. This next opportunity to send the signal S relative to the current time T is also called the target transmission time T. t .

[0247] In this case, the transmission time T for sending the signal S is determined in step S2. snd Afterwards, the user equipment UE determines at step S5 an updated value for the timing advance TA in the cell to be used when sending the signal S. In particular, such a value may be determined to correspond to a current value of the timing advance TA in the cell (e.g. previously calculated by the user equipment UE and / or used for sending a signal before the signal S). Then, at step S7, the user equipment UE finally sets the timing advance TA in the cell to the target time T. t A signal S is sent to the base station BS using the current value used as the timing advance in the cell as an updated value to be used as the timing advance TA in the cell.

[0248] However, in the context of the present disclosure, the user equipment UE may determine in step S2 that the current value of the timing advance in the cell is outdated with respect to the current time T. The user equipment UE may also determine in step S2 that the current value of the timing advance requires a significant timing advance correction (or adjustment) when the signal S is expected to be transmitted. In other words, the determination of the updated value of the timing advance TA to be used as the cell by the user equipment UE in step S2 requires updated closed-loop and / or open-loop information relative to the last received closed-loop and / or open-loop information (i.e., relative to the final timing advance command, and / or the final assistance information, and / or the final measurement). Based on such a determination that the calculation of the updated value of the timing advance TA to be used as the transmitted signal S in the cell requires updated closed-loop and / or open-loop information, the user equipment UE determines whether and / or when the user equipment UE can obtain such required information update. The user equipment UE also determines possible delay requirements attached to the transmission of the signal S. For example, the transmission of the signal S may have to be completed within a time limit guaranteed by the user equipment UE and / or more generally within a predefined transmission deadline T. r The transaction is performed in the context of a specific service level agreement (or SLA).

[0249] Taking into account the requirements for updated closed-loop and / or open-loop information as described above and possible delay requirements and / or other time constraints attached to the transmission of the signal S, the user equipment UE sends the signal S at step S2 at at least two different time opportunities T configured by the network NW. t , T p The transmission time T of the signal S is selected snd In particular, the user equipment UE may select the transmission time T between snd :

[0250] - the immediately next (or upcoming) time opportunity to send signal S relative to the current time T, also called the target transmission time T t ,as well as

[0251] -Compare the current time T and the target transmission time T t The next time opportunity to send signal S is also called the delayed transmission time T p .

[0252] Such a transmission time T snd is expressed as a time slot index or symbol index relative to a predefined reference time. Figure 4 The method for selecting such a transmission time T is further described in detail in the description of snd standards.

[0253] In step S3, in some embodiments, as will be Figure 4 As further described in detail in the description of , the user equipment UE may transmit a supplementary signal S', also referred to as a support signal S', different from the signal S. Such a support signal S' may notably be a control signal sent to the base station BS. Such a support signal S' may be intended to obtain updated closed-loop and / or open-loop information to be used for determining an updated value of the timing advance TA to be used as the signal S to be sent in the cell. The time for transmitting such a support signal S' (also referred to as the support time) may depend on the target transmission time T t In an embodiment, the time for transmitting such a support signal S' may be at the target transmission time T t In particular, the time for transmitting such a support signal S' may be delayed by the transmission time T p In an embodiment, the time for transmitting such a support signal S' may be before the target transmission time T t and delay transmission time T p For example, the user equipment UE may set the transmission time T snd Select to delay the transmission time T p , and can be transmitted at the target time T t After but after delaying the transmission time Tp The support signal S' is sent before. The support signal S' may be transmitted during a preconfigured time window (or time opportunity) set by the network NW, and the network NW enables the user equipment US to send such a support signal S' to the base station BS. Such a preconfigured time window for sending the support signal S' may be similar to or different from the time window for sending the signal S. Such a support signal S' may be significantly transmitted using the current value of the timing advance TA used in the cell. Such a time advance value for sending the support signal S' is called a support value for the timing advance. Such a support signal S' may, for example, request auxiliary information such as specific content from the base station BS. Such a support signal S' may, for example, request an update of the TAC value. Such a support signal S' may be transmitted so that the base station BS may, for example, send an updated TAC signal to the user equipment UE based on the reception timing of the support signal S' on the network side, or based on any other measurement, or based on any implementation-related decision on the network side. Such a signal S' may also correspond to an updated measurement performed by the user equipment UE. Such a signal S' may also be a request to verify the timing advance value (e.g., the current value of the timing advance) used to send S'.

[0254] In step S4, in some embodiments, as will be Figure 4 As further described in detail in the description of , the user equipment UE may receive updated closed-loop and / or open-loop information. Such reception of closed-loop and / or open-loop information at step S4 may occur notably after the transmission of the supporting signal S' at step S3. In particular, such updated closed-loop and / or open-loop information may be determined on the network side, for example based on the supporting signal S' transmitted by the user equipment UE at step S3. In particular, the updated open-loop information may also be retrieved by the user equipment UE without the need to transmit the supporting signal S' at step S3. The user equipment UE may receive the updated closed-loop and / or open-loop information at the target transmission time T t Such updated closed-loop and / or open-loop information is previously received and / or retrieved.

[0255] In another embodiment, steps S3 and S4 may be performed when the user equipment UE selects the transmission time T snd Once the user equipment UE obtains updated closed-loop and / or open-loop information for determining an updated value of the timing advance TA to be used as the transmission signal S in the cell, such a transmission time T may be actually selected. snd (Assume that the delay requirement of sending signal S enables the user equipment UE to do so). At the transmission time T of step S2 sndThe selection of may occur significantly after the expiration of a time limit after the sending of the support signal S' in step S3. For example, the user equipment UE may select the transmission time T according to the reception or non-reception of updated open-loop and / or closed-loop information in step S4 after the sending of the support signal S' in step S3. snd .

[0256] In step S5, the user equipment UE then determines the signal to be used for the selected transmission time T snd The updated value of the timing advance TA for sending the signal S in the cell. As mentioned above, in the embodiment, it is used as the update value for the timing advance TA for sending the signal S at the selected transmission time T snd The updated value of the timing advance TA for sending the signal S at may correspond to a current value of the timing advance, i.e. the timing advance value used by the user equipment UE for sending its last signal to the base station BS. In particular, such current value of the timing advance depends on the final timing advance command, the final assistance information and the final measurements (more generally, on the latest information at the current time T at which the user equipment is free to use). This may happen, for example, if the user equipment UE does not receive updated open-loop and / or closed-loop information in step S4. The user equipment UE may determine the updated value of the timing advance TA without relying on the updated closed-loop and / or open-loop information, because the user equipment UE does not consider that such updated closed-loop and / or open-loop information is needed to determine an accurate updated value of the timing advance TA, or because the delay requirements for sending the signal S do not enable the user equipment UE to wait for such updated closed-loop and / or open-loop information. Such an understanding of the updated open-loop and / or closed-loop information will be in Figure 4 The description is further described in detail in .

[0257] In another embodiment, such an updated value to be used as the timing advance TA may be determined at step S5 based on the updated closed-loop and / or open-loop information received at step S4. Figure 4 Embodiments of obtaining closed-loop and / or open-loop information enabling the user equipment UE to take into account such an update for determining an updated value of the timing advance TA to be used for sending the signal S are described in further detail in the description of .

[0258] In optional step S6, the user equipment UE may also estimate a value related to the timing advance error (also referred to as a timing error parameter) of the updated value of the timing advance TA determined in step S5. In practice, the user equipment UE may implement an incremental algorithm or a differential algorithm itself in order to, for example, determine the accuracy and / or relevance of the timing advance calculation. Thus, after each value of the timing advance TA determined by the user equipment UE in step S5, the user equipment UE may, for example, increase or decrease a stored value representing the accumulated error in the calculated timing advance values ​​during the RRC_CONNECTED mode of the user equipment UE. The criteria for increasing or decreasing such a timing error parameter will be in Figure 4 The description is further described in detail in .

[0259] Finally, in step S7, the user equipment UE uses the updated value of the timing advance TA in the cell determined in step S5 to transmit the signal at the selected transmission time T snd A signal S is sent to a base station BS.

[0260] Now refer to Figure 4 . Figure 4 is a flow chart representing the steps performed by a user equipment UE for sending a signal S to a base station BS using an updated value of a timing advance TA. In particular, Figure 4 The steps are described in further detail with respect to the following items: Figure 3 The proposed method:

[0261] In some embodiments, the transmission time T is selected snd , and in particular the selection of the user equipment UE to select a transmission time relative to the target transmission time T t The delayed transmission time T p ,

[0262] - obtaining the angle of the updated closed loop and / or open loop information possibly triggered by the user equipment UE by sending a support signal S' to the base station BS,

[0263] - User Equipment UE implements timing error parameters.

[0264] In step S1 as described above, the user equipment UE intends to send a signal S to the base station BS. In particular, such signal S is intended to be sent using an updated value of the timing advance TA in the cell in order to compensate as accurately as possible for the propagation delay between the user equipment UE sending the signal S and the network reference point (which in the context of the present disclosure is considered to be the location of the base station BS) receiving such signal S. In the proposed method, the user equipment UE will further Figure 4 The standard is described in further detail in:

[0265] - Select the transmission time T of signal S snd ,

[0266] - may send a supporting signal S' different from signal S, and

[0267] - Determine an updated value of the timing advance TA to be used for sending the signal S in the cell.

[0268] At step S20, the user equipment UE determines the final command time C associated with the final timing advance command received from the base station BS (via the final closed loop information). N and the current time T. This first time gap is then compared with a preconfigured first gap threshold known to the user equipment UE. Equivalently, the final command time C N With effective time T ths If at step S20, such a final command time C N is at the effective time T ths Before (or equivalently, if the last command time C N and the current time T exceeds a preconfigured first gap threshold), the user equipment UE determines that the last TAC signal (and therefore the correction parameters related to the timing advance command value contained in such last TAC signal, also referred to as final closed-loop correction) is out of date at the current time T. In this case, the user equipment UE determines that it needs updated information to relevantly determine an updated value of the timing advance TA to be used as for sending the signal S. In particular, in this case, the user equipment UE determines that the updated value of the timing advance TA to be used as for sending the signal S should be different from the current timing advance value.

[0269] If the user equipment UE determines at step S20 that the information needs to be updated due to the outdatedness of the last TAC signal, the user equipment UE determines at step S22 the transmission time T of the signal S. snd Whether it is predictable, for example, whether the signal S can be sent based on the configured authorization. If the user equipment UE determines in step S22 that such transmission of the signal S is predictable, the user equipment UE may transmit a support signal S' to the base station BS in step S42. In particular, such a support signal S' may include information about the transmission time T of the signal S. snd In contrast, if at step S22 the user equipment UE determines that such transmission of the signal S may not be predictable (e.g., if there is no configured authorization for sending the signal S), the user equipment UE further proceeds to step S30, which will be described in further detail. However, if at step S20 the final command time C N is at the effective time T ths After (or equivalently, if the final command time C NThe first time gap between the current time T of executing step S20 and the time T of executing step S20 is lower than the preconfigured first gap threshold, the user equipment UE determines that the time C of the final command is the same as the time T of the final command. N The associated final TAC signal (and thus the correction parameters or final closed-loop correction related to the timing advance command value contained in such a TAC signal) is still relevant at the current time T. In particular, the user equipment UE may rely on the value of the timing advance command contained in such a final TAC signal as a guide to adjust the updated value to be used as the timing advance TA relative to the current timing advance value. To this end, at step S21, the user equipment UE compares the final timing advance command value contained in such a final TAC signal (i.e. the correction parameters corresponding to the final closed-loop correction) with a correction threshold value N set by the user equipment UE or predefined or sent by the base station BS to the user equipment UE. ths，CL Such a preconfigured correction threshold N ths，CL It may be set, for example, between 30 and 50 and may be expressed in steps, samples or time units.

[0270] If the timing advance command value contained in such a final TAC signal is determined to be lower than the preconfigured correction threshold N in step S21, ths，CL , then the amount of closed-loop correction determined by the user equipment UE to be applied to the current timing advance value is not significant: in other words, the propagation delay to be compensated between the user equipment UE and the network reference point has not changed significantly compared to the current value of the timing advance last calculated by the user equipment UE at a time before the current time T. Therefore, the updated value of the timing advance TA determined by the user equipment UE at step S41 after step S21 may be determined to correspond to the current value of the timing advance TA. In a specific embodiment, at step S41, the user equipment UE may also update the timing error parameter by reducing the timing error parameter value, because the user equipment UE determines that the updated timing advance value determined at step S41 is reasonably accurate taking into account the current time T. However, if at step S21 the timing advance command value contained in the final TAC signal exceeds a preconfigured correction threshold N ths，CL , then the user equipment UE determines in step S21 that the current value of the timing advance TA requires a significant timing advance correction when the expected transmission signal S is determined. In particular, if the final closed-loop correction is considered significant in the final TAC signal, the user equipment UE determines that it requires update information to determine an updated value to be used as the timing advance TA. Since the timing advance command value has a finite size (and thus may only indicate a finite correction), such an updated value may potentially be more significant than the timing advance command value included in the final TAC signal.

[0271] To this end, after step S21, the user equipment UE determines in step S30 whether it can be updated at the auxiliary time A after the current time T. N+1 and possibly by retrieving updated assistance information according to a time-related parameter. In other words, the user equipment UE predicts when an upcoming transmission of updated open-loop information from the network NW will occur and checks the corresponding updated assistance time A N+1 Is it acceptable (or fast enough) for the user equipment UE (eg, regarding time-related parameters). Such time-related parameters may be, for example, related to the transmission deadline T r The terms "acceptable" and "fast enough" should be understood here as the transmission deadline T for sending the signal S. r Possibly, "acceptable" and "fast enough" should be understood here as delaying the transmission time T p The expressions "acceptable" and "soon enough" should also be understood as before the expiration of a given timer related to a time-related parameter. In particular, the user equipment UE may, based on a preconfigured period of assistance information transmission determined or estimated by the user equipment UE, notably by using a previous assistance time A N-1 , A N-2 Waiting and / or final auxiliary time A N , to predict when such next transmission of updated open-loop information from the network NW will occur.

[0272] If, at step S30, the user equipment UE determines that such updated open-loop information can be sent by the network NW quickly enough, for example at the target transmission time T t After but after delaying the transmission time T p Before, the user equipment UE in step S43 (including Figure 3 In step S2), it is determined that the transmission time T snd Select to delay the transmission time T p , so that the user equipment UE voluntarily gives up the next upcoming time opportunity to send the signal S (i.e., at the target transmission time T t ) in order to wait for receiving the updated open loop. In such a case in step S43, the user equipment UE may not need to send any support signal S': the user equipment UE has determined that the updated open loop transmission will be within the updated auxiliary time A within a predictable time. N+1 occurs, and the user equipment UE will determine the updated value to be used as the timing advance TA based on such updated open loop transmission. However, if at step S30 the user equipment UE predicts that no transmission of open loop information from the network NW will occur quickly enough (e.g. the updated auxiliary time A predicted by the user equipment UE) N+1Later than the transmission deadline T of signal S r ), the user equipment UE decides, in step S40 after step S30, to determine an updated value of the timing advance TA without updated open-loop and / or closed-loop information. In particular, the user equipment UE may determine the updated value of the timing advance TA as the current value of the timing advance (and thus based on the final TAC signal). In a particular embodiment, in step S40, the user equipment UE may also update the timing error parameter by increasing the value of the timing error parameter, because the user equipment UE determines that the determined updated value of the timing advance TA may not be accurate in view of the significant correction implied in the final TAC signal. In such a case, the user equipment UE may decide to set the transmission time T snd Select the target transmission time T t , because the user equipment UE determines that there is no interest in deferring the sending of the signal S (while no updated information may be expected). However, updating the timing error parameter enables the user equipment UE to evaluate the accuracy of the timing advance achieved by the user equipment UE, and in such a case at step S40, it is evaluated that the updated value of the determined timing advance TA may not be accurate because it has lost the updated information.

[0273] Similarly, at step S30, the user equipment UE may also determine or anticipate an updated measurement time M associated with the updated measurement to be obtained by the user equipment UE. N+1 . Auxiliary time A applied to update N+1 The reasoning can also be applied to the updated measurement time M N+1 .

[0274] In step S20, the user equipment UE also sends the final command time C of the final TAC signal received by the user equipment UE. N The final assistance time A associated with the final assistance information and / or the final measurement respectively when the user equipment UE is free to use N and / or final measurement time M N If in step S20, the final command time C N At the final assist time A N and / or final measurement time M N Before any one (or both) of the TAC signal, the user equipment UE proceeds to step S23. In particular, as described above, the user equipment UE proceeds to such step S23 independently of the expiration (or non-expiration) of the last TAC signal.

[0275] At step S23, the user equipment UE determines whether the final open loop information reflects a significant timing advance correction to the current value of the timing advance. To this end, at step S23, the user equipment UE may compare the open loop correction provided by the final assistance information and / or the final measurement, such open loop correction also referred to as a self-correction parameter. Then at step S23, such self-correction parameter is compared with a preconfigured self-correction threshold N ths,OL Such a preconfigured self-correction threshold N ths,OL In order to quantify the significance of the open-loop correction, in an embodiment, such a preconfigured self-correction threshold N ths,OL Can be equal to the preconfigured correction threshold N ths，CL If the user equipment UE determines that the self-calibration parameter obtained based on such final open-loop information exceeds the pre-configured self-calibration threshold N ths,OL , the user equipment UE may determine that the final open loop information reflects a significant timing advance adjustment (i.e., a significant open loop correction) of the current value of the timing advance. In an embodiment, if the current value of the timing advance is equal to the current value of the timing advance, the user equipment UE may determine that the final open loop information reflects a significant timing advance adjustment (i.e., a significant open loop correction) of the current value of the timing advance. N-1 Compared with the previous location measurements performed by the user equipment UE at the final measurement time M N If the final measurement performed results in a dramatic change in the location of the user equipment UE (e.g., more than one or several kilometers), the user equipment UE may consider the final open loop information to reflect a significant timing advance adjustment. N The final assistance information performed results in the satellite SAT being updated according to the satellite ephemeris relative to, for example, the previous assistance time A. N-1 If a substantial movement of the previous satellite position is obtained, the user equipment UE may consider the final open loop information to reflect the significant timing advance adjustment.

[0276] If, at step S23, the user equipment UE determines that the final open loop information reflects a significant timing advance adjustment to be applied to the current value of the timing advance, the user equipment UE determines that it needs update information in order to accurately determine the updated value of the timing advance TA to be used when sending the signal S, because such an updated value TA may potentially differ significantly from the current value of the timing advance. To this end, the user equipment UE may transmit a support signal S' to the base station BS at step S44 following step S23. In particular, such a support signal S' may be a signal requesting updated assistance information and / or an updated timing advance command. In a specific embodiment, the user equipment UE may transmit such a support signal S' using a support value used as the timing advance corresponding to the current value of the timing advance TA (thus, the final open loop information is taken into account when sending the support signal S'). Thus, the user equipment UE potentially at least partially compensates for the actual propagation delay between the user equipment UE and the network reference point at the current time T. In particular, such a support signal S' may be transmitted at the next immediately following time opportunity to request assistance information configured by the network NW. The sending of the signal S is attached to a specific transmission deadline T r In the case of a transmission cut-off time T, the support signal S' may also include an indication of a potential reconfiguration of the requesting auxiliary information transmission and / or updated TAC signal, so that the user equipment UE can transmit the signal at the transmission cut-off time T r In an embodiment, the user equipment UE may also continue to perform the measurement at the updated measurement time M in step S44. N+1 The request may also optionally relate to the configuration of measurement gaps (and hence measurement opportunities) in case measurements on the user equipment UE side can only be made during measurement gaps configured by the network. The reception (or non-reception) of the updated assistance information after such transmission of the support signal S' at step S44 is not controlled by the user equipment UE. Therefore, at step S44, a transmission cut-off time T is provided, for example, r The user equipment UE reflecting the delay requirement for sending the signal S can use the transmission time T snd Select to delay the transmission time T p , notably in order to wait for possible updated auxiliary information and / or updated TAC signal. Then, the user equipment UE can wait until the expiration of a predefined timer after sending the supporting signal S' according to the latency requirement to send the signal S (even if no updated information is obtained). The user equipment UE can also wait until the expiration of a predefined timer after sending the supporting signal S' according to the latency requirement to send another supporting signal S'. Notably, if the supporting signal S' is pre-transmitted, the user equipment UE can also select the transmission time T of the signal S. sndAs the target transmission time T t .

[0277] If, at step S23, the user equipment UE determines that the final open loop information does not reflect a significant timing advance adjustment compared to the current value of the timing advance (e.g., if the user equipment UE determines that its position and the position of the satellite SAT are relative to, for example, at auxiliary time A N-1 and measurement time M N-1 If the previously obtained open-loop information has not changed or has not changed significantly), the user equipment UE continues to determine whether such final open-loop information is outdated relative to the current time T in step S31 after step S23. To this end, in step S31, the user equipment UE may determine whether the current time T is outdated relative to the final auxiliary time A. N and / or final measurement time M N Then, the user equipment UE may compare such a second time gap with a preconfigured second gap threshold. Equivalently, the user equipment UE may calculate the final auxiliary time A N and / or final measurement time M N With effective time T ths In particular, if in step S31, the user equipment UE determines the final auxiliary time A N and / or final measurement time M N At the effective time T ths After (or equivalently, if the last auxiliary time A N and / or the last measurement time M N ) and the current time T is lower than a preconfigured second gap threshold, the user equipment UE considers that the final open-loop information is recent (i.e., not outdated) with respect to the current time T. In this case, the user equipment UE determines in step S46 after step S31 that the final open-loop information correlates to the fact that no significant timing advance correction has to be applied to the current value of the timing advance used to send the signal S in consideration of the current time T. Therefore, in step S46, the user equipment determines an updated value of the timing advance TA without the need to update the information. In particular, in step S46, the user equipment UE may determine that the updated value of the timing advance TA to be used to send the signal S corresponds to the current value of the timing advance TA. In a specific embodiment, in step S46, the user equipment UE may also update the timing error parameter by reducing the timing error parameter value, because the user equipment UE determines that the updated timing advance value TA should not be significantly different from the current value of the timing advance. In such a case, in step S46, the user equipment UE may snd Select the target transmission time T t , because the user equipment UE does not need to postpone the transmission of the signal S to wait for any updated information.

[0278] However, if in step S31, the user equipment UE determines the final auxiliary time A N and / or final measurement time M N At the effective time T ths Before (or equivalently, if the final auxiliary time A N and / or final measurement time M N If the second time gap between any one of the time intervals A and the current time T exceeds the preconfigured second gap threshold, the user equipment UE considers that the final open-loop information is outdated. In an embodiment, the user equipment UE may also determine the final auxiliary time A in step S31. N and the final measurement time M N Such a third time gap can then be compared with a preconfigured third gap threshold in order to determine the consistency of the final open-loop information. N and / or final measurement time M N and the current time T exceeds a preconfigured second gap threshold, or if the third time gap exceeds a preconfigured third gap threshold, the final open-loop information may be considered outdated at step S31. In the case of outdated final open-loop information, the user equipment UE determines at step S31 that it needs to update the information because it considers the final assistance information and / or the final measurement (and therefore the indication of insignificant open-loop correction determined at step S23) to be unreliable at the current time T. For example, at the final assistance time A N and / or final measurement time M N The user equipment UE and / or the satellite SAT may have moved significantly between the current time T. In such a case, at step S45, the user equipment UE continues to transmit a support signal S' requesting updated open-loop information in a similar manner to step S44. In an embodiment, the user equipment UE may also continue to perform updated measurements at step S45 (assuming that its hardware capabilities and / or preconfigured time opportunities allow this). The user equipment UE may then significantly depend on the potential delay requirements for sending the signal S, on the potential updated auxiliary time A N+1 and / or updated measurement time M N+1 To determine the transmission time T for sending signal S snd In particular, the user equipment UE that provides the delay requirement can set the transmission time T snd Select to delay the transmission time T p , in order to wait for potential update information. For example, if the support signal S' is transmitted at the target time T t is transmitted before, and if the updated information is transmitted at the target transmission time T tIf it is received before, the user equipment UE can also set the transmission time T snd Select the target transmission time T t In such a case, the signal S may be sent using the updated value of the timing advance TA determined based on the update information. Then, the timing error parameter may be updated by reducing the timing error parameter value. However, even if the target transmission time T t If the updated information is received before the target transmission time T t The user equipment UE may also transmit the support signal S' before the transmission time T , and if the delay requirement does not allow the user equipment UE to give up its immediately upcoming time opportunity for sending the signal S, the user equipment UE may also change the transmission time T snd Select the target transmission time T t In this case, the signal S may be sent using an updated value of the timing advance TA determined based on the final open-loop and closed-loop information. The timing error parameter may then be updated by increasing the timing error parameter value.

[0279] Figure 5 , Figure 6 and Figure 7 Further provided are examples for sending a signal S to a base station BS using an updated value of a timing advance TA according to various embodiments of the present disclosure. Figure 5 , Figure 6 and Figure 7 A timeline representing signals sent and received by a user equipment UE and signals from measurements performed by the user equipment UE. Signals and information received by the user equipment UE from other entities such as a base station BS and more generally the network NW are represented by downward arrows pointing to the timeline. Signals and information sent by the user equipment UE and measurements performed by the user equipment UE are represented by upward arrows pointing out of the timeline. Some of the represented sending, receiving and measuring steps are associated with respective times. In Figure 5 , Figure 6 and Figure 7 In each of , time T represents the current time T considering the proposed method.

[0280] Reference Figure 5 , Figure 6 and Figure 7 , the user equipment UE intends to send a signal S to the base station BS at the current time T. For example, such a signal S may be a data, SR and / or BSR signal. A configuration time opportunity T for sending such a signal S is proposed t , T p .exist Figure 5 , Figure 6 and Figure 7 The above shows two time opportunities T t , T p, but in other possible implementations, there may be more or fewer time opportunities for sending signals to the base station BS. The time opportunity for sending the signal S to the base station BS includes at least the target transmission time T t and target transmission time T t The later the transmission time is, the p .

[0281] See also Figure 5 , at the current time T stage:

[0282] - the user equipment UE has received from the network NW final assistance information associated with the last (or final) assistance time A0,

[0283] - After transmitting three uplink signals to the base station BS (as indicated by the three upward arrows), the user equipment UE has also received three timing advance command (or TAC) signals from the base station BS at the corresponding command times C0, C1 and C2. In particular, such command times C0, C1 and C2 are calculated on the base station BS side and do not directly depend on the transmission time of the transmitted uplink signals. The user equipment UE receives such TAC signals whenever it sends an uplink signal to the base station BS. Therefore, the latest closed loop information is associated with the final command time C2.

[0284] In other words, at the current time T, the user equipment UE has received a more recent (and therefore up-to-date) timing advance adjustment from the closed-loop information than the timing advance adjustment from the open-loop information.

[0285] In the context of the present disclosure, at the current time T, the user equipment UE can then t , T p The time window is selected to send the signal S to the base station BS. In particular, Figure 5 In the implementation mode, the transmission time T snd Such selection may include determining an updated assistance time A1 when the user equipment UE can retrieve updated assistance information. The user equipment UE may notably predict such updated assistance time A1 based on the last assistance time A0 and the configured periodicity of assistance information transmission. Such configured periodicity of assistance information transmission may be determined and / or calculated by the user equipment UE based on data related to the last assistance time A0. Such data related to the last assistance time A0 may include a plurality of assistance times before the last assistance time A0 (not in Figure 5 ). Figure 5 In the case shown, the user equipment UE predicts that the updated auxiliary time A1 will occur at the target transmission time T t After that and after delaying the transmission time T pThe user equipment UE may also determine that the user equipment UE will be able to postpone the transmission time T p The measurement is performed at a previous measurement time M0. Such a measurement time M0 is significantly predicted or anticipated by the user equipment UE based on its hardware capabilities (e.g., the user equipment UE has the capability to perform measurements whenever such measurements are needed) and / or a time opportunity provided by the network NW (e.g., providing the user equipment UE with a measurement opportunity at the measurement time M0).

[0286] In this case, the user equipment UE will select the transmission time T at the current time T snd To delay the transmission time T p In other words, despite being provided with an upcoming time opportunity to transmit signal S (i.e., target transmission time T t ), but the user equipment UE will intentionally decide to postpone such transmission to a later time opportunity (i.e., the target transmission time T p ) in order to obtain further updated assistance information relative to the last assistance information received at the last assistance time A0.

[0287] Based on such updated assistance information associated with the updated assistance time A1 and the updated measurement performed at the updated measurement time M0, the user equipment UE can, based on such updated open-loop information, perform the measurement at the deferral time T p When the signal S is sent, the value to be used as the timing advance TA in the cell is updated.

[0288] In a particular embodiment, the TAC signals received at the respective command times C0, C1 and C2 may all indicate a large correction for the updated value to be used as the timing advance TA in the cell relative to the last value used by the user equipment UE as the timing advance in the cell. Such a large correction may, for example, indicate a switching of the timing advance value between 50 and 63 in each TAC signal. In such a case, the user equipment UE may also change the transmission time T to 1 based on the requirement to perform a relatively large timing advance correction. snd Select to delay the transmission time T p , such a considerable timing advance correction is quantifiable via open loop adjustment.

[0289] In a specific embodiment, it is assumed that potential delay requirements and / or timing constraints to be observed by the user equipment UE when sending the signal S are obtained by postponing the transmission time T in such a way that p Send signal S to meet, then the transmission time T snd is selected to delay the transmission time T p For example, refer to Figure 5 , the timing constraint may request the user equipment UE to transmit within the potential transmission deadline T r Signal S was sent before.

[0290] Reference Figure 6 , before the current time T:

[0291] - the user equipment UE has received the last assistance information from the network NW at the last assistance time A0,

[0292] - the user equipment UE has performed the last measurement at the last measurement time M0,

[0293] - After transmitting the uplink signal to the base station BS (as indicated by the upward arrow), the user equipment UE has also received the last timing advance command (or TAC) signal from the base station BS at the last command time C0. In particular, such last assistance time A0, last measurement time M0 and last command time C0 are considered outdated at the current time T, because they are valid at the time T0. ths Previously, for example, it was preset by the user equipment UE or sent to the user equipment UE. In other words, at the current time T, the user equipment UE determines that the final information from both the open-loop source and the closed-loop source that enables updating the value of the timing advance to be used as the transmission signal S is out of date. Equivalently, the time gap between the final command time C0 and the current time may be compared with a preconfigured first gap threshold, and the time gap between each of the final assistance time A0 and the final measurement time M and the current time T may be compared with a preconfigured second gap threshold. For simplicity, such a gap threshold is considered to be equal to and corresponds to the time gap between the current time T and the effective time T ths In an embodiment, the time gap between the final assistance time A0 and the final measurement time M0 (also referred to as a third time gap) may also be compared with a preconfigured third gap threshold.

[0294] The user equipment UE can t , T p The time window is selected to send the signal S to the base station BS. Figure 6 In the context of , since the last assistance information, measurement and TAC are considered outdated, the user equipment UE determines that it needs to update the information to determine an accurate updated value of the timing advance to be used as in the cell when sending the signal S. In an embodiment, since the third time gap between the final assistance time A0 and the final measurement time M0 may exceed a preconfigured third gap threshold, the user equipment UE may determine that the information needs to be updated.

[0295] Therefore, the user equipment UE can determine at the current time T whether it can t , T pAn uplink transmission is transmitted to the base station BS at a previous time opportunity T' to send a signal S to the base station BS. For example, in case of periodic reporting performed by the user equipment UE, such an uplink transmission may be predictable for the user equipment UE.

[0296] exist Figure 6 In such a context (and assuming that the user equipment UE has a time opportunity T' to do so), the user equipment UE may decide to transmit a supplementary signal S' to the base station BS, such supplementary signal S' being different from the signal S, as in Figure 6 The above is represented at time T'.

[0297] After transmitting such a supplementary signal S', the user equipment UE may potentially receive an updated TAC signal at the updated command time C1.

[0298] Based on such an updated TAC signal, the user equipment UE updates the value to be used as the timing advance in the cell as described above and transmits the signal at the selected target transmission time T according to the updated command time C1. t Or postpone the transmission time T p The transmission time T snd Send signal S.

[0299] In a specific embodiment, it is assumed that potential delay requirements and / or timing constraints to be observed by the user equipment UE when sending the signal S are obtained by postponing the transmission time T in such a way that p Send signal S to meet, then the transmission time T snd is selected to delay the transmission time T p For example, refer to Figure 6 , the timing constraint may request the user equipment UE to transmit within the potential transmission deadline T r Before sending signal S (this can further take into account some internal processing time).

[0300] Reference Figure 7 , before the current time T:

[0301] - the user equipment UE has received the last assistance information from the network NW at the last assistance times A0 and A1,

[0302] - the user equipment UE has performed the last measurement at the last measurement time M0 and M1,

[0303] - After transmitting the uplink signal to the base station BS (as indicated by the upward arrow), the user equipment UE has also received the last timing advance command (or TAC) signal from the base station BS at the last command time C0. In particular, as in Figure 7 As shown above, the last command time C0 is before the last assistance time A1.

[0304] In particular, Figure 7 In the context of , the last assistance information received at the last assistance time A1 is considered to indicate a significant timing advance adjustment relative to the last timing advance value used by the user equipment UE in the cell (e.g. for performing the last uplink signal). In other words, the self-correction parameter provided by the last assistance information exceeds a preconfigured self-correction threshold N ths,OL In addition, such last auxiliary information is considered outdated because the last auxiliary time A1 is within the valid time T ths Before.

[0305] Therefore, at the current time T, the user equipment UE determines, based on such last assistance information received, that a potentially significant timing correction is to be performed to update the value to be used as the timing advance TA in the cell when transmitting the signal S. However, since such last assistance information is considered by the user equipment UE to be outdated at the current time T, such last assistance information may be irrelevant for determining the updated value to be used as the timing advance TA for transmitting the signal S.

[0306] Therefore, in Figure 7 In such a case represented above, the user equipment UE may determine the supported timing advance value based on the last assistance information received at the last assistance time A1. The user equipment UE may then use the supported timing advance value to send a support signal S' to the base station BS (assuming that the user equipment UE has a time opportunity to do so). Such a supported timing advance value may significantly correspond to the current value of the timing advance determined by the user equipment based on the last information at a time before the current time T. In particular, assuming that such measurement gaps are under the control of the network NW, such a support signal S' may request the transmission of updated assistance information and / or updated timing advance commands and / or the configuration of measurement gaps (or times) for measurements.

[0307] After receiving the updated assistance information at the updated assistance time A2, the user equipment UE can then determine an updated value of the timing advance TA to be used for sending the signal S. The user equipment UE then determines an updated value of the timing advance TA to be used for sending the signal S, depending on the updated assistance time A2, the support time for sending the support signal S' and / or the delay requirement for sending the signal S, at the target transmission time T t Or postpone the transmission time T p The transmission time T snd Send signal S.

[0308] In a specific embodiment, it is assumed that potential delay requirements and / or timing constraints to be observed by the user equipment UE when sending the signal S are obtained by postponing the transmission time T in such a way that p Send signal S to meet, then the transmission time T snd is selected to delay the transmission time Tp For example, refer to Figure 7 , the timing constraint may request the user equipment UE to transmit within the potential transmission deadline T r Signal S was sent before.

Claims

1. A method performed by a user equipment for signaling a base station with an updated value of a timing advance, the user equipment being connected to the base station, the base station corresponding to a cell supported by a non-geostationary satellite of a satellite communication network, the user equipment determining the value of the timing advance based on at least: - data relating to assistance information associated with an assistance time received by said user equipment, - data relating to measurements obtained by said user equipment and associated with a measurement time, - data relating to a timing advance command received from the network associated with a command time, The method comprises the following steps: The transmission time of the signal is selected from at least the following: - the target transmission time of the signal, and -- a delayed transmission time of the signal, the delayed transmission time being later than the target transmission time; sending the signal to the base station at the transmission time using the updated value of the timing advance, The selected transmission time is selected based on a combination of at least two of the following factors: - time-related parameters, - data relating to a final timing advance command associated with a final command time, - data relating to the final measurement associated with the time of the final measurement, - data relating to final assistance information associated with a final assistance time, - data relating to said final measurement time, - data relating to the time of said final command, and - data relating to said final assistance time.

2. The method according to claim 1, further comprising the steps of: A supporting signal different from the signal is transmitted to the base station, the supporting signal being sent at a supporting time dependent on the target transmission time of the signal.

3. The method according to claim 2, wherein the data related to the assistance information and the data related to the measurement providing the value of the self-correction parameter are used by the user equipment to determine the value of the timing advance, And among them, The transmission of the support signal is also based on at least one of the following criteria: - a first time gap between the final command time and the current time exceeds a preconfigured first gap threshold, or - the final command time is before the final assistance time, and: -- a second time gap between the final auxiliary time and / or the final measurement time and the current time exceeds a preconfigured second gap threshold, or - A value of the self-correction parameter determined based on data related to the final assistance information and / or the final measurement exceeds a preconfigured self-correction threshold.

4. The method according to claim 2 or 3, wherein the time-related parameter is related to the validity time of the data used to determine the value of the timing advance, and wherein: The transmission of the support signal is also based on the following standards: - Any one of the final command time, the final measurement time and the final assistance time is before the valid time.

5. The method according to any one of claims 2 to 4, wherein: The support signal is transmitted using a support value of the timing advance, the support value of the timing advance being determined based on a combination of at least two elements of at least the following items: - said time-dependent parameter, - data related to said final timing advance command, - data relating to said final measurement, - data related to the final auxiliary information, - data relating to said final measurement time, - data relating to the time of said final command, and - data relating to said final assistance time.

6. The method according to any one of claims 2 to 5, wherein: The support signal is an element of at least the following: - uplink reference signals, such as sounding reference signals, - control signals, - Cache status reporting, and - Scheduling request.

7. The method according to any one of claims 1 to 6, wherein: if: - data relating to updated assistance information is predicted to be associated with an updated assistance time between said target transmission time and said deferred transmission time, and / or - data relating to the updated measurement are determined to be associated with an updated measurement time between said target transmission time and said deferred transmission time, Then the transmission time is selected as the deferred transmission time.

8. The method according to any one of claims 1 to 7, wherein the data relating to the timing advance command providing the value of the correction parameter is used by the user equipment to determine the value of the timing advance, And among them, if: - the gap between the final command time and the current time is lower than a preconfigured first gap threshold, and - the value of the correction parameter determined based on the data related to the final timing advance command exceeds a preconfigured correction threshold, and - data relating to updated assistance information are predicted to be associated with an updated assistance time later than the final assistance time and later than the current time, the updated assistance time being between the target transmission time and the deferred transmission time, and / or data relating to updated measurements are determined to be associated with an updated measurement time later than the final measurement time and later than the current time, the updated measurement time being between the target transmission time and the deferred transmission time, Then the transmission time is selected as the deferred transmission time.

9. The method according to claim 7 or 8, wherein: Determination of an updated value of the timing advance for sending the signal is performed based at least on the updated assistance information associated with the updated assistance time and / or the updated measurement associated with the updated measurement time.

10. The method according to any one of claims 1 to 9, wherein the user equipment updates a value of a timing error parameter related to error estimation when determining the value of the timing advance, and wherein: The method further comprises the following steps: If the transmission time is selected as the target transmission time, the timing error parameter is updated.

11. The method according to claim 10, wherein the data related to the timing advance command providing the value of the correction parameter is used by the user equipment to determine the value of the timing advance, and the data related to the assistance information and the data related to the measurement providing the value of the self-correction parameter are used by the user equipment to determine the value of the timing advance, And among them, The updating of the timing error parameter includes: if: - the gap between the final command time and the current time is lower than a preconfigured first gap threshold, and a value of the correction parameter determined based on data related to the final timing advance command exceeds a preconfigured correction threshold, and data relating to updated assistance information is predicted to be associated with an updated assistance time later than the final assistance time, the updated assistance time being later than the postponed transmission time, and / or data relating to updated measurements is determined to be associated with an updated measurement time later than the final measurement time, the updated measurement time being later than the postponed transmission time, Then increase the value of the timing error parameter, and / or - if the gap between said final command time and said current time is below a preconfigured alternative first gap threshold, and a value of the correction parameter determined based on data related to the final timing advance command is below a preconfigured alternative correction threshold, - or if the final command time is before one of the final assistance time and the final measurement time, and the value of the self-correction parameter determined based on data relating to the final assistance information and / or based on data relating to the final measurement is below a preconfigured alternative self-correction threshold, and a gap between the final auxiliary time and / or the final measurement time and the current time is below a preconfigured alternative second gap threshold, Then reduce the value of the timing error parameter.

12. The method according to any one of claims 1 to 11, wherein the time-related parameter is associated with a transmission deadline, and wherein: The transmission time of the signal is selected to be before the transmission cut-off time.

13. The method according to any one of claims 1 to 12, further comprising the steps of: If a third time gap between the final measurement time and the final assistance time exceeds a preconfigured third gap threshold, an updated measurement is performed at an updated measurement time.

14. A user equipment, the user equipment being configured to send a signal to a base station using an updated value of a timing advance, the user equipment being connected to the base station, the base station corresponding to a cell supported by a non-geostationary satellite of a satellite communication network, The user equipment determines a value of the timing advance based on at least the following items: - data relating to assistance information associated with an assistance time received by said user equipment, - data relating to measurements obtained by said user equipment and associated with a measurement time, - data relating to a timing advance command received from said network and associated with a command time, The user device comprises a processor and a non-transitory computer-readable medium comprising instructions stored thereon, the instructions, when executed by the processor, configuring the user device to: Select the transmission time of the signal from the following: - the target transmission time of the signal, and --postponing the transmission time, the postponed transmission time being later than the target transmission time; sending the signal to the base station at the transmission time using the updated value of the timing advance, in, The selected transmission time is selected based on a combination of at least two of the following: - time-related parameters, - data relating to a final timing advance command associated with a final command time, - data relating to the final measurement associated with the time of the final measurement, - data relating to final assistance information associated with a final assistance time, - data relating to said final measurement time, - data relating to the time of said final command, and - data relating to said final assistance time.

15. A computer program product comprising program instruction codes stored on a computer readable medium for executing the method according to any one of claims 1 to 13.

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