Methods for determining a repetition number, terminal device and network device

Abstract

Methods for determining a repetition number, terminal device and network device This disclosure relates to a method for determining a repetition number, the method being performed by a terminal device (600) implementing coverage enhancement, wherein the method comprises the following steps: obtaining (201) mapping information between device parameter information of the terminal device (600) and repetition number information, wherein a repetition number indicates a number of repeated signal transmission attempts performed by the terminal device (600); and if transmission of the signal fails, determining (202), based on the mapping information, whether a coverage enhancement level should be increased or whether a current coverage enhancement level should be maintained with an increased repetition number.

Description

[0001] 202405303

[0002] - 1 -

[0003] Description

[0004] Methods for determining a repetition number, terminal device and network device

[0005] This disclosure relates to methods for determining a repetition number for signal transmission and to a corresponding terminal device and a corresponding network device.

[0006] Within the last decades, a rapidly increasing number of terminal devices are used in networks all over the world and in many different applications. With such increase, network resource availability in networks becomes more and more limited for said terminal devices. Additionally, terminal devices are used more and more in areas, which may have reduced network accessibility, such as in indoor scenarios. In order to efficiently communicate despite those challenges, terminal devices implement coverage enhancement, CE.

[0007] CE is achieved through repetition in time, retransmission, and power-boosting in-band and guard band operating modes. Reliable CE is achieved by the repeated transmission of data and control signaling. Each signal transmission can be configured to repeat for a designated number of times, indicated by a repetition number, in order to achieve higher success opportunities at the desired coverage level.

[0008] Repeated transmissions and, in particular, power-boosting, however, increase the power consumption of a terminal device implementing CE. Since power efficiency is becoming more and more important for terminal devices, in particular for terminal devices running on batteries and limited power availability, the increase of power consumption is an increasing issue.

[0009] Accordingly, it is an object of this disclosure to present methods for determining a repetition number, a terminal device and a network device, with which the above- mentioned problem is solved or mitigated. 202405303

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[0011] The above-mentioned object is solved by the subject-matter of the attached independent claims. Further embodiments are disclosed in the attached dependent claims, as well as in the following description and the figures.

[0012] According to a first aspect, a method for determining a repetition number is presented. The method is performed by a terminal device implementing coverage enhancement, CE. The method comprises the following steps: obtaining mapping information between device parameter information of the terminal device and repetition number information, wherein a repetition number indicates a number of repeated signal transmission attempts performed by the terminal device; and, if transmission of the signal fails, determining, based on the mapping information, whether a coverage enhancement level should be increased or whether a current coverage enhancement level should be maintained with an increased repetition number.

[0013] An advantage herein is that an adaptive repetition number for repeated signal transmission attempts, performed by a terminal device, is provided. In particular, the repetition number can be adaptively adjusted depending on the device parameter information. This allows an increase of the repetition number, if transmission of a signal using a current repetition number failed, whilst otherwise a current CE level, and therefore e.g. a current transmission power of said current CE level, is maintained and not increased. This achieves a higher possibility of successful signal transmission, even if network resource availability is limited, due to the increased repetition number, whilst power consumption may be reduced due to adaptively maintaining the current CE level, and therefore maintaining a current transmission power, before or instead of switching to a next CE level. Using the mapping information, and therewith coupling the selection of whether to increase the CE level or whether to maintain the CE level and merely increase the repetition number to the device parameter information of the terminal device, allows an adaptive increase or maintaining of the CE level based on parameters of the terminal device, such that said increase of maintaining of the CE level may be performed considering characteristics of the terminal device. All this contributes to an improved energy efficiency of a transmission of a to be transmitted signal. 202405303

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[0015] The device parameter information of the terminal device may be any information related to a device parameter, which is related to characteristics of the terminal device. Optionally, the device parameter information may be information related to device parameters such as an energy level of the terminal device, a quality of service, QoS, parameter of the terminal device, a mobility state of the terminal device, etc. This will be described in more detail below, with respect to specific example embodiments. In general, the device parameter information may be any information related to device parameters, based on which a selection of whether to increase a CE level or whether to maintain a current CE level and increase the repetition number, may be taken.

[0016] The repetition number information may be any information indicating or allowing determination of whether to increase of the repetition number at current CE level, or whether to increase the CE level. For example, the repetition number information may comprise an indication of an exact repetition number, to which the repetition number should be increased if the current CE level is maintained, or the repetition number information comprises an indication of an amount of repetitions, by which the current repetition number should be increased if the current CE level is maintained, or the repetition number information may indicate that the repetition number shall be increased to an average between the current repetition number and a repetition number of a next higher CE level, if the current CE level is maintained. Alternatively, the repetition number information may also merely relate to a “yes” or “no” indication of the increase of repetition number, in particular if the terminal device has a pre-configured increase of repetition number for such cases, in which the current CE level is to be maintained but the repetition number increased. This disclosure is not limited in that regard and other indications of increase of the repetition number may be implemented.

[0017] That a transmission of the signal fails may be determined, for example, in case a signal has been attempted to be transmitted for a number of times related to a current repetition number, but the transmission of the signal was not successful, or not sufficiently successful, in order for the signal to be considered successfully transmitted. This may be the case, for example, if an acknowledgement, ACK, is not received or a negative acknowledgement, NACK, is received from the network device in response to 202405303

[0018] - 4 - transmitting the signal. For example, that a transmission of a signal fails may be determined in case a random access, RA, failure occurs.

[0019] Coverage enhancement, CE, in the context of this application, relates to the enhancement of coverage of a network in areas, in which network access and / or network resources may be limited. The CE is implemented using CE levels, for example four CE levels, i.e., level 1 , level 2, level 3, and level 4, wherein each CE level is defined by CE parameters, in particular a CE level specific repetition number, and a CE level specific transmission power. If transmission of a signal is not successful in a current CE level, the CE level may be increased. With increase of CE level, the specific repetition number and / or specific transmission power is increased. Those CE levels and their specific parameters are, for example, pre-determined by the network.

[0020] According to at least one embodiment of the disclosure, the terminal device obtains the mapping information from a network device. Alternatively, the mapping information is stored on the terminal device and obtained from a storage of the terminal device.

[0021] An advantage of obtaining the mapping information from the network device may be that a suitable adaptation to network specific characteristics may be achieved, in that the network device can adapt the mapping information, and therewith influence in which cases the CE level is increased, and in which cases the CE level is maintained and the repetition number increased. An advantage of obtaining the mapping information from the storage of the terminal device is that less overhead is generated in the network.

[0022] According to at least one embodiment of the disclosure, the device parameter information comprises information concerning at least one device parameter and the device parameter information comprises at least one of the following:

[0023] - an energy level threshold of the terminal device;

[0024] - a mobility state of the terminal device; and

[0025] - a quality of service, QoS, requirement.

[0026] An advantage of using a threshold of the energy level of the terminal device in the mapping information is that, based on the available energy of the terminal device, the 202405303

[0027] - 5 - determination, whether to increase the CE level or whether to maintain the CE level and increase the repetition number may be selected. Since an increase of CE level results in a higher energy consumption of the terminal device, it may therefore be determined that the CE level is related to the energy level of the terminal device, such that in particular terminal devices with lower available energy may maintain their CE level and only increase their repetition number.

[0028] An advantage of using the mobility state of the terminal device in the mapping information is that the mobility of the terminal device may have a significant impact on the success rate of transmitting a signal. For example, in case a terminal device is stationary, it may be assumed that no change of success rate of transmitting a signal can be expected, whilst a non-stationary terminal device may experience a change of success rate of signal transmission, already due to it moving to a different area, such that, for example, in case of a stationary mobility state, the mapping information may indicate a direct increase of CE level, whilst in non-stationary mobility state, the mapping information may indicate a maintaining of the CE level and increase of repetition number.

[0029] The mobility state may, for example, comprise two states: “stationary” and “non- stationary”. Additionally, the mobility state may also consider further states, such as states related to a velocity of the terminal device, e.g., “pedestrian”, “vehicle”, etc., or other types of movement.

[0030] An advantage of considering a QoS requirement in the mapping information may be that specific QoS requirements may, for example, indicate a higher priority of a transmission, a higher requirement regarding packet loss, regarding latency, etc. For certain QoS requirements, it may therefore be advantageous to directly increase the CE level, in case of failure of signal transmission with a current CE level. Other QoS requirements, however, may allow the maintaining of the current CE level with increased repetition number. 202405303

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[0032] All of the above have the advantage that a more detailed adaptation of the method for determining the repetition number to specific characteristics of the terminal device is achieved.

[0033] According to at least one advantageous embodiment of the disclosure, the following examples for determining, based on the mapping information, whether a coverage enhancement level should be increased or whether a current coverage enhancement level should be maintained with an increased repetition number, may be implemented:

[0034] - if an energy level of the terminal device is equal to or greater than the energy level threshold, increasing the coverage enhancement level, and if an energy level of the terminal device is lower than the energy level threshold, maintaining the current coverage enhancement level and increasing the repetition number; and / or

[0035] - if the current mobility state of the terminal device indicates a first mobility state, increasing the coverage enhancement level, and if the current mobility state of the terminal device indicates a second mobility state, maintaining the current coverage enhancement level and increasing the repetition number, wherein the second mobility state indicates a higher mobility than the first mobility state.

[0036] A combination of those two examples is also possible. In that case, priority may be given to either the determination made based on the energy level, or based on the mobility state, whichever is suitable in the desired implementation. For example, if the current mobility state is the first mobility state and the energy level of the terminal device is equal to or greater than the energy level threshold, the CE level is increased, and in all other cases, i.e. , if the current mobility state is the second mobility state and the energy level of the terminal device is equal to or greater than the energy level threshold, or if the current mobility state is the first mobility state and the energy level of the terminal device is lower than the energy level threshold, or if the current mobility state is the second mobility state and the energy level of the terminal device is lower than the energy level threshold, the current coverage enhancement level is maintained and the repetition number is increased. Other combinations of those examples are, however, also possible. 202405303

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[0038] According to at least one advantageous embodiment of the disclosure, the increased repetition number is:

[0039] - a repetition number of the current coverage enhancement level increased to an average between the repetition number of the current coverage enhancement level and a repetition number of the next higher coverage enhancement level; or

[0040] - the repetition number of the current coverage enhancement level being increased by a predetermined value; or

[0041] - the repetition number of the current coverage enhancement level being increased by a value indicated in the mapping information.

[0042] This may either be directly indicated in the mapping information, or may be preconfigured and the mapping information, in that case, may comprise an indication of whether to increase the repetition number according to the pre-configured increase of repetition number, while maintaining the CE level.

[0043] According to at least one embodiment of the disclosure, the method further comprises:

[0044] - if transmission of the signal using the increased repetition number fails, increasing the coverage enhancement level.

[0045] An advantage thereof is that an efficient tradeoff between saving energy and increasing a success rate of signal transmission may be achieved. This may be adapted, however, by one or more repetitions of performing the step of: maintaining a current coverage enhancement level with a further increased repetition number, if it was determined that the CE level is to be maintained, before the CE level is eventually increased.

[0046] According to at least one advantageous embodiment of the disclosure, the signal is a signal related to a random access channel, RACH, procedure, or the signal is a signal related to a data transmission procedure.

[0047] This way, the advantages discussed above may be achieved in RACH procedure, as well as in data transmission. 202405303

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[0049] According to a second aspect, a method for determining a repetition number is provided. The method being performed by a network device. The method comprises the following steps: obtaining device information of a terminal device implementing coverage enhancement; determining mapping information between device parameter information based on the device information of the terminal device and repetition number information, wherein a repetition number indicates a number of repeated signal transmission attempts performed by the terminal device, and the mapping information indicates whether a coverage enhancement level should be increased or whether a current coverage enhancement level should be maintained with an increased repetition number if transmission of the signal fails; and sending the mapping information to the terminal device.

[0050] The second aspect corresponds to the embodiment of the first aspect, according to which the network device determines and provides the mapping information. The further embodiments and examples discussed above with regard to the first aspect, correspondingly also can be applied to the second aspect. Accordingly, also the advantages discussed above with regard to the first aspect, correspondingly apply to the second aspect.

[0051] The device information of the terminal device may comprise directly information concerning the device parameter information used for the mapping information, such as an energy level, a mobility state, or a QoS requirement of the terminal device, or may be used to derive said device parameter information, such as, for example, an ID of the terminal device, or a type of the terminal device, etc.

[0052] According to at least one embodiment of the disclosure, the network device sends the mapping information throguh a system block information, SIB, message and / or through a radio resource configuration, RRC, reconfiguration message.

[0053] An advantage thereof is that already existing messaging may be used to provide the mapping information by the network device, such that network resources may be saved. 202405303

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[0055] According to at least one embodiment, the method according to the first aspect or the method according to the second aspect is implemented in a non-terrestrial network, NTN, or in a 5G new radio, NR, network.

[0056] Both application cases are particularly advantageous for the above-discussed methods. 5G NR networks experience a particular large increase in terminal devices and, therefore, are subject to the above-discussed limitation of network resources for each device. NTNs additionally experience the above-discussed limitation of network resources, because due to large distances between satellites and the terminal devices on the earth, beams used for signal transmission become very wide. Thus, cell coverage spans many dozens of kilometers for low earth orbit, LEO, networks and may even span hundreds of kilometers for geostationary orbit, GSO, networks. Due to the large coverage per satellite beam, and the exploding number of devices with varying capabilities and categories, the number of devices per beam may be particularly large. This additionally amounts to the limited resource availability per device in NTNs.

[0057] Furthermore, both types of networks support low-cost loT type of devices, which have a limited energy availability. NTNs, for example, support loT operation, based upon NB- loT and MTC devices. Additionally, there are plans to include support for NR based RedCap devices. To avoid spectrum being a bottleneck for communication in NTNs as well as in 5G NR networks, application of the above-discussed methods is particularly advantageous.

[0058] According to a third aspect, a terminal device is provided. The terminal device comprises a transceiver unit and a processing unit and the terminal device is configured to implement the method according to any one of the above-discussed first aspect or embodiments of the first aspect.

[0059] According to a fourth aspect, a network device is provided. The network device comprises a transceiver unit and a processing unit and the network device is configured to implement the method according to any one of the above-discussed second aspect or embodiments of the second aspect. 202405303

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[0061] According to a fifth aspect, a computer program product is provided. The computer program product comprises instructions, which, when executed on a terminal device, implement the method according to any of the first aspect or the embodiments of the first aspect and, when executed on a network device, implement the method according to any of the second aspect or the embodiments of the second aspect.

[0062] According to a sixth aspect, a computer-readable storage medium is provided. The computer-readable storage medium comprises the computer program product according to the fifth aspect.

[0063] Advantages and embodiments of the third to sixth aspect correspond, in general, to those advantages and embodiments of the first and second aspect discussed in detail above. Any feature disclosed in the context of the first and / or second aspect may be, correspondingly, applied to any of the third to sixth aspect.

[0064] The above-mentioned aspects of the disclosure and their embodiments will be explained in more detail in the following with the aid of the drawings. The description, however, shall not be limited to those detailed examples and is defined by the attached claims.

[0065] In the drawings:

[0066] Figure 1 shows an NTN system, to which the methods of this disclosure may be applied;

[0067] Figure 2 (A) shows a flowchart of a method for determining a repetition number, implemented by a terminal device, according to one embodiment;

[0068] Figure 2 (B) shows a flowchart of a method for determining a repetition number, implemented by a network device, according to one embodiment; 202405303

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[0070] Figure 3 (A) shows a flowchart of a method for determining a repetition number, implemented by a terminal device, according to another embodiment;

[0071] Figure 3 (B) shows a flowchart of a method for determining a repetition number, implemented by a network device, according to another embodiment;

[0072] Figure 4 (A) shows a flowchart of a method for determining a repetition number, implemented by a terminal device, according to yet another embodiment;

[0073] Figure 4 (B) shows a flowchart of a method for determining a repetition number, implemented by a network device, according to yet another embodiment;

[0074] Figure 5 (A) shows a flowchart of a method for determining a repetition number, implemented by a terminal device, according to yet another embodiment;

[0075] Figure 5 (B) shows a flowchart of a method for determining a repetition number, implemented by a network device, according to yet another embodiment;

[0076] Figure 6 shows a schematic drawing of a terminal device according to one embodiment; and

[0077] Figure 7 shows a schematic drawing of a network device according to one embodiment.

[0078] Figure 1 shows, as an example, an NTN system 1 , to which the methods of this disclosure may be applied. The NTN system 1 may be, for example, a low earth orbit, LEO, system, or a medium earth orbit, MEO, system, or a geostationary earth orbit, 202405303

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[0080] GSO, system, etc. The NTN system 1 comprises a satellite 2, which in the context of this application serves as an example for a network device. In different examples, however, also different network devices may be implementing the corresponding method of this application.

[0081] The satellite 2 provides service using beams 3, via which the satellite 2 sends signals. Those beams 2 form beam footprints 4, covering service areas, which may be covering large areas, as discussed above, due to the distance between the satellite 2 and the earth’s surface, at or above which service is provided.

[0082] The NTN system 1 further comprises several pieces of user equipment 5, UE, which in the context of this application serves as example or equivalent to terminal devices discussed above. The pieces of UE 5, which are served by the satellite 2 using NTN services, are located in the area of the beam footprints 4 and communicate with the satellite 2 according to known communication techniques, such as, for example, NB-loT communication techniques, NR NTN techniques, etc. The pieces of UE 5 may comprise, for example, NB-loT devices, MTC devices, RedCap devices, or any other NTN capable device known in the art.

[0083] To efficiently communicate with the satellite 2, the UEs 5 implement coverage enhancement, CE, according to which different levels of CE may be used to implement transmission repetition, power boosting, etc.

[0084] It is to be understood that the types of communication and types of devices discussed in the context of Figure 1 are to be understood as examples of a system, to which the embodiments of this disclosure may be applied. Alternatively, however, the embodiments of this application may also be applied to other systems, such as 5G NR systems, or others, with their respective devices and communication techniques as known in the art.

[0085] Figure 2 (A) shows a flowchart of a method for determining a repetition number, implemented by a terminal device, according to one embodiment. For example, the 202405303

[0086] - 13 - method as shown in Figure 2 (A) may be implemented by any of the UEs 5 discussed with regard to Figure 1 above.

[0087] In a step 201 , the terminal device obtains a mapping information between device parameter information of the terminal device and repetition number information. The repetition number information relates to a repetition number of sending a signal by the terminal device, the repetition number indicating a number of repeated signal transmission attempts performed by the terminal device.

[0088] In said step 201 , the terminal device may obtain the mapping information from a network device. Alternatively, the terminal device may have the mapping information pre-configured and stored and may obtain the mapping information from a storage of the terminal device.

[0089] In a step 202, if transmission of the signal fails, the terminal device determines, based on the mapping information obtained in step 201 , whether a CE level should be increased to a next higher CE level, or whether a current CE level should be maintained and the repetition number for sending the signal should be increased from a current repetition number of the current CE level to an increased repetition number. If the CE level is determined to be maintained, other parameters of the current CE level are not increased, in particular a transmission power for transmitting the signal is not increased.

[0090] For example, the device parameter information may comprise at least one of the following: an energy level threshold of the terminal device, a mobility state of the terminal device, and a quality of service requirement.

[0091] The increased repetition number may be, for example, a repetition number of the current CE level increased to an average between the repetition number of the current CE level and a repetition number of the next higher CE level. Alternatively, the increased repetition number may be, for example, the repetition number of the current CE level being increased by a predetermined value. Further alternatively, the increased repetition number may be, for example, the repetition number of the current CE level being increased by a value indicated in the mapping information. 202405303

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[0093] The signal, which the terminal device attempts to send to the network device, may be, for example, a signal related to a random access channel, RACH, procedure, or it may be a signal related to a data transmission procedure.

[0094] In a step 203, which is performed by the terminal device if it was determined to maintain the CE level in step 202, the terminal device continues to transmit the signal to the network device using the same CE level parameters as before, in particular a same transmission power as before, but with the increased repetition number.

[0095] In a step 204, which is performed by the terminal device if it was determined to increase the CE level in step 202, the terminal device continues to transmit the signal to the network device using the CE level parameters of the next higher CE level, in particular a higher transmission power.

[0096] In a step 205, which is performed by the terminal device if transmission of the signal in step 203 with the maintained current CE level but increased repetition number fails again, the terminal device switches to the next higher CE level and continues to transmit the signal to the network device using the CE level parameters of the next higher CE level, as in step 204. Alternatively, however, step 202 may also be repeated and the decision whether to increase the CE level or whether to maintain the CE level and further increase the repetition number, may be performed instead, before eventually increasing the CE level, if retransmission at the maintained CE level but with increased repetition numbers is unsuccessful.

[0097] At any point in the above-discussed method, if transmission of the signal is successful, the method may be ended and transmission of a next signal may be performed, again taking advantage of the above-discussed method.

[0098] Figure 2 (B) shows a flowchart of a method for determining a repetition number, implemented by a network device, according to one embodiment. For example, the method as shown in Figure 2 (B) may be implemented by the satellite 2 discussed with regard to Figure 1 above. 202405303

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[0100] In a step 211 , the network device obtains device information of a terminal device implementing coverage enhancement. For example, the terminal device sends the device information to the network device, or the network device obtains the device information from a storage of the network device or from a core network.

[0101] In a step 212, the network device determines mapping information between device parameter information based on the device information of the terminal device and repetition number information. The mapping information indicates to the terminal device, whether a CE level should be increased or whether a current CE level should be maintained with an increased repetition number if transmission of the signal fails.

[0102] In a step 213, the network device sends the mapping information to the terminal device. For example, the network device may send the mapping information to the terminal device through a system block information, SIB, message and / or through a radio resource configuration, RRC, reconfiguration message.

[0103] The method as shown in Figure 2 (B) may be combined with the method as shown in Figure 2 (A) such that the terminal device obtains, in step 201 , the mapping information by receiving the mapping information sent by the network device in step 213.

[0104] Alternatively, however, the terminal device may also obtain the mapping information in step 201 differently, for example the mapping information may be pre-configured in the terminal device.

[0105] Figure 3 (A) shows a flowchart of a method for determining a repetition number, implemented by a terminal device, according to another embodiment. In this embodiment, an energy level threshold is used as device parameter information in the mapping information. Details, which have been described above, with regard to the other Figures, may apply here accordingly and will not be descried again. Reference is made to the discussion of those features above. 202405303

[0106] - 16 -

[0107] In a first step 301 , the terminal device obtains the mapping information, wherein the mapping information comprises an energy level threshold as device parameter information.

[0108] In a step 302, the terminal device determines whether a random access, RA, procedure fails. This RA failure may be determined according to any technique known in the art.

[0109] If the RA procedure is successful, the method ends and no further steps are performed.

[0110] If the RA procedure fails, the terminal device determines in a step 303, whether an energy level of the terminal device is equal to or greater than the energy level threshold obtained with the mapping information.

[0111] If in step 303, the terminal device determines that the energy level of the terminal device is equal to or greater than the energy level threshold, the terminal device increases a CE level to a next higher CE level in a step 304.

[0112] If in step 303, the terminal device determines that the energy level of the terminal device is below the energy level threshold, the terminal device maintains the current CE level and sets a repetition number to an increased repetition number based on the mapping information in a step 305.

[0113] Figure 3 (B) shows a flowchart of a method for determining a repetition number, implemented by a network device, according to another embodiment. In this embodiment, an energy level threshold is used as device parameter information in the mapping information. Details, which have been described above, with regard to the other Figures, may apply here accordingly and will not be descried again. Reference is made to the discussion of those features above.

[0114] In a step 311 , the network device configures an energy level threshold and generates mapping information between the energy level threshold and repetition number information, which is to be used by a terminal device to determine whether to maintain a CE level and to increase a repetition number, or whether to increase a CE level directly. 202405303

[0115] - 17 -

[0116] The configuration of the energy level threshold may be performed, for example, based on device information of the terminal device, such as a device type, or a type of energy supply, etc.

[0117] In a step 312, the network device sends the mapping information to a terminal device.

[0118] The method as shown in Figure 3 (B) may be combined with the method as shown in Figure 3 (A) such that the terminal device obtains, in step 301 , the mapping information by receiving the mapping information sent by the network device. Alternatively, however, the terminal device may also obtain the mapping information in step 301 differently, for example the mapping information may be pre-configured in the terminal device.

[0119] Figure 4 (A) shows a flowchart of a method for determining a repetition number, implemented by a terminal device, according to yet another embodiment. In this embodiment, a mobility state of the terminal device is used as device parameter information in the mapping information. Details, which have been described above, with regard to the other Figures, may apply here accordingly and will not be descried again. Reference is made to the discussion of those features above.

[0120] In a first step 401 , the terminal device obtains the mapping information, wherein the mapping information comprises information regarding a mobility state of the terminal device as device parameter information.

[0121] In a step 402, the terminal device determines whether a random access, RA, procedure fails. This RA failure may be determined according to any technique known in the art.

[0122] If the RA procedure is successful, the method ends and no further steps are performed.

[0123] If the RA procedure fails, the terminal device determines in a step 403, whether a mobility state of the terminal device stationary. 202405303

[0124] - 18 -

[0125] If in step 403, the terminal device determines that the mobility state of the terminal device is stationary, the terminal device increases a CE level to a next higher CE level in a step 404.

[0126] If in step 403, the terminal device determines that the mobility state of the terminal device is non-stationary, the terminal device maintains the current CE level and sets a repetition number to an increased repetition number based on the mapping information in a step 405.

[0127] Figure 3 (B) shows a flowchart of a method for determining a repetition number, implemented by a network device, according to yet another embodiment. In this embodiment, information concerning a mobility state of a terminal device is used as device parameter information in the mapping information. Details, which have been described above, with regard to the other Figures, may apply here accordingly and will not be descried again. Reference is made to the discussion of those features above.

[0128] In a step 411 , the network device configures for which mobility states a CE level shall be directly increased and for which mobility states a CE level shall be maintained with increased repetition number and generates mapping information between the mobility states and repetition number information. The mobility states may comprise two mobility states, i.e. , “stationary”, and “non-stationary”, or may comprise further states such as different types of non-stationary mobility states, for example depending on a velocity of a terminal device, i.e., “ < 50 km / h”, “between 50 km / h and 100 km / h”, “> 100 km / h”, etc., or depending on a detected type of mobility, such as “pedestrian”, “bicycle”, “vehicle”, etc.

[0129] In a step 412, the network device sends the mapping information to a terminal device.

[0130] The method as shown in Figure 4 (B) may be combined with the method as shown in Figure 4 (A) such that the terminal device obtains, in step 401 , the mapping information by receiving the mapping information sent by the network device. Alternatively, however, the terminal device may also obtain the mapping information in step 401 202405303

[0131] - 19 - differently, for example the mapping information may be pre-configured in the terminal device.

[0132] Figure 5 (A) shows a flowchart of a method for determining a repetition number, implemented by a terminal device, according to yet another embodiment. In this embodiment, an energy level threshold and a mobility state are used as device parameter information in the mapping information. Details, which have been described above, with regard to the other Figures, may apply here accordingly and will not be descried again. Reference is made to the discussion of those features above.

[0133] In a first step 501 , the terminal device obtains the mapping information, wherein the mapping information comprises an energy level threshold and a mobility state of the terminal device as device parameter information.

[0134] In a step 502, the terminal device determines whether a random access, RA, procedure fails. This RA failure may be determined according to any technique known in the art.

[0135] If the RA procedure is successful, the method ends and no further steps are performed.

[0136] If the RA procedure fails, the terminal device determines in a step 503, whether an energy level of the terminal device is equal to or greater than the energy level threshold obtained with the mapping information and whether a mobility state of the terminal device is “stationary”.

[0137] If in step 503, the terminal device determines that both cases are “true”, the terminal device increases a CE level to a next higher CE level in a step 504.

[0138] If in step 503, the terminal device determines that not both cases are “true”, the terminal device maintains the current CE level and sets a repetition number to an increased repetition number based on the mapping information in a step 505.

[0139] Figure 5 (B) shows a flowchart of a method for determining a repetition number, implemented by a network device, according to yet another embodiment. In this 202405303

[0140] - 20 - embodiment, an energy level threshold and mobility state is used as device parameter information in the mapping information. Details, which have been described above, with regard to the other Figures, may apply here accordingly and will not be descried again. Reference is made to the discussion of those features above.

[0141] In a step 511 , the network device configures an energy level threshold and determines for which mobility states, the CE level shall be maintained with increased repetition number or increased directly, and generates mapping information between the energy level threshold, the mobility state, and repetition number information.

[0142] In a step 512, the network device sends the mapping information to a terminal device.

[0143] The method as shown in Figure 5 (B) may be combined with the method as shown in Figure 5 (A) such that the terminal device obtains, in step 501 , the mapping information by receiving the mapping information sent by the network device. Alternatively, however, the terminal device may also obtain the mapping information in step 501 differently, for example the mapping information may be pre-configured in the terminal device.

[0144] Additionally, in any of the methods according to Figures 2 to 5, also a QoS requirement may be used as device parameter information, wherein for example QoS requirements indicating a higher priority and / or a requirement for a lower latency may be used in the mapping to indicate a direct increase of the CE level, whereas a lower priority and / or a less strict requirement on latency may be used in the mapping information to indicate a maintaining of a CE level with increased repetition number.

[0145] Figure 6 shows a schematic drawing of a terminal device 600 according to one embodiment. The terminal device 600 may be, for example, the terminal device described with regard to Figure 1 or may be a terminal device in a different network.

[0146] The terminal device 600 comprises a transceiver unit 601 , a storage unit 602, and a processing unit 603. 202405303

[0147] - 21 -

[0148] The transceiver unit 601 is configured to send signals to a network device and to receive signals from the network device. In particular, the transceiver unit 601 is configured to receive the above-discussed mapping information from the network device, and to send signals to the network device using CE.

[0149] The storage unit 602 is configured to store the received mapping information and / or to store pre-configured mapping information.

[0150] The processing unit 603 is configured to obtain the mapping information between device parameter information of the terminal device and repetition number information. The processing unit 603 is further configured to determine, if transmission of the signal fails, based on the mapping information, whether a coverage CE should be increased or whether a current CE level should be maintained with an increased repetition number.

[0151] Further details and features of the terminal device 600 may be found in the description of the embodiments above, which may apply to this terminal device 600 accordingly and are not repeated herein.

[0152] Figure 7 shows a schematic drawing of a network device 700 according to one embodiment. The network device 700 may be, for example, the network device described with regard to Figure 1 or may be a network device in a different network.

[0153] The network device 700 comprises a transceiver unit 701 and a processing unit 702.

[0154] The transceiver unit 701 is configured to send signals to a terminal device and to receive signals from the terminal device. In particular, the transceiver unit 601 is configured to receive device information from the terminal device, and to send the above-discussed mapping information to the terminal device.

[0155] The processing unit 702 is configured to determine mapping information between device parameter information based on the device information of the terminal device and repetition number information, wherein the mapping information indicates whether a 202405303

[0156] - 22 -

[0157] CE level should be increased or whether a current CE level should be maintained with an increased repetition number if transmission of the signal fails.

[0158] Further details and features of the network device 700 may be found in the description of the embodiments above, which may apply to this network device 700 accordingly and are not repeated herein.

[0159] All methods shown in Figures 2 to 5 may be implemented by the terminal device and network device, respectively, which are shown in Figures 6 and 7 or in Figure 1 . Features, which are disclosed with regard to one embodiment may be suitably combined with the methods and devices disclosed in the other embodiments.

[0160] 202405303

[0161] - 23 -

[0162] List of reference signs

[0163] 1 NTN system

[0164] 2 satellite

[0165] 3 beam

[0166] 4 beam footprint

[0167] 5 user equipment

[0168] 201 to 205 method steps

[0169] 211 to 213 method steps

[0170] 301 to 305 method steps

[0171] 311 to 312 method steps

[0172] 401 to 405 method steps

[0173] 411 to 412 method steps

[0174] 501 to 505 method steps

[0175] 511 to 512 method steps

[0176] 600 terminal device

[0177] 601 transceiver unit

[0178] 602 storage unit

[0179] 603 processing unit

[0180] 700 network device

[0181] 701 transceiver unit

[0182] 702 processing unit

Claims

202405303- 24 -Claims1. Method for determining a repetition number, the method being performed by a terminal device (600) implementing coverage enhancement, wherein the method comprises the following steps:- obtaining (201 ) mapping information between device parameter information of the terminal device (600) and repetition number information, wherein a repetition number indicates a number of repeated signal transmission attempts performed by the terminal device (600); and- if transmission of the signal fails, determining (202), based on the mapping information, whether a coverage enhancement level should be increased or whether a current coverage enhancement level should be maintained with an increased repetition number.

2. The method according to claim 1 , wherein:- the terminal device (600) obtains the mapping information from a network device(700); or- the mapping information is stored on the terminal device (600) and obtained from a storage of the terminal device (600).

3. The method according to claim 1 or 2, wherein the device parameter information comprises information concerning at least one device parameter and the device parameter information comprises at least one of the following:- an energy level threshold of the terminal device (600);- a mobility state of the terminal device (600); and- a quality of service requirement.

4. The method according to claim 3, wherein the determining (202), based on the mapping information, whether a coverage enhancement level should be increased or whether a current coverage enhancement level should be maintained with an increased repetition number comprises:- if an energy level of the terminal device (600) is equal to or greater than the energy level threshold, increasing (304) the coverage enhancement level, and if an energy level202405303- 25 - of the terminal device (600) is lower than the energy level threshold, maintaining (305) the current coverage enhancement level and increasing the repetition number; and / or- if the current mobility state of the terminal device (600) indicates a first mobility state, increasing (404) the coverage enhancement level, and if the current mobility state of the terminal device (600) indicates a second mobility state, maintaining (405) the current coverage enhancement level and increasing the repetition number, wherein the second mobility state indicates a higher mobility than the first mobility state.

5. The method according to any one of claims 1 to 4, wherein the increased repetition number is:- a repetition number of the current coverage enhancement level increased to an average between the repetition number of the current coverage enhancement level and a repetition number of the next higher coverage enhancement level; or- the repetition number of the current coverage enhancement level being increased by a predetermined value; or- the repetition number of the current coverage enhancement level being increased by a value indicated in the mapping information.

6. The method according to any one of claims 1 to 5, further comprising:- if transmission of the signal using the increased repetition number fails, increasing (205) the coverage enhancement level.

7. The method according to any one of claims 1 to 6, wherein the signal is a signal related to a random access channel, RACH, procedure, or the signal is a signal related to a data transmission procedure.

8. Method for determining a repetition number, the method being performed by a network device (700), wherein the method comprises the following steps:- obtaining (211 ) device information of a terminal device (600) implementing coverage enhancement;- determining (212) mapping information between device parameter information based on the device information of the terminal device (600) and repetition number information, wherein a repetition number indicates a number of repeated signal202405303- 26 - transmission attempts performed by the terminal device (600), and the mapping information indicates whether a coverage enhancement level should be increased or whether a current coverage enhancement level should be maintained with an increased repetition number if transmission of the signal fails; and- sending (213) the mapping information to the terminal device (600).

9. The method according to claim 8, wherein the network device (700) sends (213) the mapping information using a system block information, SIB, message and / or using a radio resource configuration, RRC, reconfiguration message.

10. The method according to any one of claims 1 to 7 or 8 to 9, wherein the method is implemented in a non-terrestrial network, NTN, or in a 5G new radio, NR, network.

11. A terminal device (600) comprising a transceiver unit and a processing unit, wherein the processing unit is configured to implement the method according to any one of claims 1 to 7 and 10.

12. A network device (700), wherein the network device (700) comprises a transceiver unit and a processing unit and the network device (700) is configured to implement the method according to any of claims 7 to 10.

13. A computer program product comprising instructions, which, when executed on a terminal device (600), implement the method according to any one of claims 1 to 7 and 10 and, when executed on a network device (700), implement the method according to any of claims 7 to 10.

14. A computer-readable storage medium comprising the computer program product according to the claim 13.

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