Method and apparatus for determining the transmission start time of an uplink signal

Abstract

This specification describes a terminal device comprising: means for receiving first configuration information including an indication that a first downlink reference signal is used by the terminal device as a time reference for applying a timing advance value when transmitting an uplink signal according to a first transmit configuration indicator TCI state; means for receiving the first downlink reference signal; means for determining a transmission start time for an uplink signal transmitted according to a first TCI state based on the time of reception of the first downlink reference signal and a timing advance value; and means for transmitting an uplink signal according to the transmission start time and the first TCI state.

Description

Background Art

[0001] New Radio (NR) was first introduced in 3GPP Release 15, and the latest release is Release 18, which is still under development. The technology described herein relates to improving the performance of wireless long-distance communication networks, specifically but not limited to, new radio long-distance communication networks.

Summary of the Invention

[0002] In a first aspect, this document describes a terminal device comprising means for receiving first configuration information including an indication that a first downlink reference signal is used by a terminal device as a time reference for the application of a timing advance value when transmitting an uplink signal according to a first transmission configuration indicator (TCI) state, means for receiving the first downlink reference signal, means for determining a transmission start time for an uplink signal transmitted according to the first TCI state based on the reception time of the first downlink reference signal and the timing advance value, and means for transmitting the uplink signal according to the transmission start time and the first TCI state.

[0003] In some examples, the TCI state configuration information may include the first configuration information. The TCI state configuration information can include a first TCI state configuration corresponding to the first TCI state and a second TCI state configuration corresponding to the second TCI state, where the first TCI state configuration includes an indication that the first downlink reference signal is used by the terminal device as a time reference for the application of a timing advance value when transmitting an uplink signal according to the first TCI state, and the second TCI state configuration includes an indication that the first downlink reference signal is used by the terminal device as a time reference for the application of a timing advance value when transmitting an uplink signal according to the second TCI state.

[0004] In other examples, the first configuration information may indicate multiple TCI states, and for the multiple TCI states, the first downlink reference signal is used as a time reference for applying a timing advance value when transmitting an uplink signal according to any of the multiple TCI states, and the multiple TCI states include a first TCI state and a second TCI state.

[0005] The terminal device may further provide means for switching from transmitting the uplink signal according to a first TCI state to transmitting the uplink signal according to a second TCI state, while maintaining a first downlink reference signal as a time reference for applying a timing advance value when transmitting the uplink signal according to a second TCI state. The first downlink reference signal may be transmitted using a third beam that is wider than the first beam associated with the first TCI state and the second beam associated with the second TCI state. The third beam may spatially overlap the first and second beams.

[0006] The first downlink reference signal may be a synchronization signal block (SSB) or a channel state information reference signal (CSI-RS). The first configuration information may be contained within a Radio Resource Control (RRC) configuration or reconfiguration message, or within a Medium Access Control (MAC) control element.

[0007] The terminal device may further include means for receiving new configuration information for configuring the transmission of an uplink signal by the terminal device; means for determining that the new configuration information received by the terminal device does not include an indication that a particular downlink reference signal is used by the terminal device as a time reference for applying a timing advance value when transmitting an uplink signal; and means for determining a time reference according to an instruction stored in the terminal device in response to the determination that the new configuration information received by the terminal device does not include an indication that a particular downlink reference signal is used by the terminal device as a time reference for applying a timing advance value when transmitting an uplink signal.

[0008] The instruction may indicate that the determination is based on the time of reception of a downlink reference signal associated with one of a set of activated TCI states, where the time reference is detected by the shortest path delay. An activated TCI state in the set of activated TCI states may be associated with a single transmit-receive point (TRP), or with a specific set of control resources (CORESET), or with a pool index of a specific CORESET.

[0009] In another example, the instruction may indicate that when a terminal device switches from using an initial TCI state to using a new TCI state, the time reference is determined based on the time of reception of the downlink reference signal associated with the initial TCI state.

[0010] In other examples, the instruction may indicate that it is determined based on the time of reception of a reference signal that is indicated to have a spatial relationship with a physical uplink control channel (PUCCH) resource assigned to the terminal device.

[0011] In a second embodiment, the Specification describes a base station comprising means for transmitting first configuration information to a terminal device, including an indication that a first downlink reference signal is used by the terminal device as a time reference for applying a timing advance value when transmitting an uplink signal according to a first transmit configuration indicator TCI state.

[0012] In some examples, TCI state configuration information may include first configuration information. The TCI state configuration information may include a first TCI state configuration corresponding to a first TCI state and a second TCI state configuration corresponding to a second TCI state, wherein the first TCI state configuration includes an indication that it is used by the terminal device as a time reference for applying a timing advance value when a first downlink reference signal transmits an uplink signal according to the first TCI state, and the second TCI state configuration includes an indication that it is used by the terminal device as a time reference for applying a timing advance value when a first downlink reference signal transmits an uplink signal according to the second TCI state.

[0013] In other examples, the first configuration information may indicate multiple TCI states, and for the multiple TCI states, the first downlink reference signal is used as a time reference for applying a timing advance value when transmitting an uplink signal according to any of the multiple TCI states, and the multiple TCI states include a first TCI state and a second TCI state.

[0014] The first downlink reference signal may be transmitted using a third beam that is wider than the first beam associated with the first TCI state and the second beam associated with the second TCI state. The third beam may spatially overlap the first and second beams.

[0015] The first downlink reference signal may be a synchronization signal block (SSB) or a channel status information reference signal (CSI-RS). The first configuration information may be contained within a radio resource control (RRC) configuration or reconfiguration message, or within a media access control (MAC) control element.

[0016] In a third embodiment, this specification describes a method comprising the steps of: receiving first configuration information by a terminal device, including an indication that a first downlink reference signal is used by the terminal device as a time reference for applying a timing advance value when transmitting an uplink signal according to a first transmit configuration indicator TCI state; receiving the first downlink reference signal by the terminal device; determining a transmit start time for an uplink signal to be transmitted according to the first TCI state based on the time of reception of the first downlink reference signal and the timing advance value; and transmitting one or more uplink signals by the terminal device according to the transmit start time and the first TCI state.

[0017] In some examples, TCI state configuration information includes first configuration information. The TCI state configuration information may include a first TCI state configuration corresponding to a first TCI state and a second TCI state configuration corresponding to a second TCI state, wherein the first TCI state configuration includes an indication that it is used by the terminal device as a time reference for applying a timing advance value when a first downlink reference signal transmits an uplink signal according to the first TCI state, and the second TCI state configuration includes an indication that it is used by the terminal device as a time reference for applying a timing advance value when a first downlink reference signal transmits an uplink signal according to the second TCI state.

[0018] In other examples, the first configuration information may indicate multiple TCI states, and for the multiple TCI states, the first downlink reference signal is used as a time reference for applying a timing advance value when transmitting an uplink signal according to any of the multiple TCI states, and the multiple TCI states include a first TCI state and a second TCI state.

[0019] The method may further include the step of having a terminal device switch from transmitting the uplink signal according to a first TCI state to transmitting the uplink signal according to a second TCI state, while keeping the first downlink reference signal as a time reference for applying a timing advance value when transmitting the uplink signal according to a second TCI state. The first downlink reference signal may be transmitted using a third beam that is wider than the first beam associated with the first TCI state and the second beam associated with the second TCI state. The third beam may spatially overlap the first and second beams.

[0020] The first downlink reference signal may be a synchronization signal block (SSB) or a channel status information reference signal (CSI-RS). The first configuration information may be contained within a radio resource control (RRC) configuration or reconfiguration message, or within a media access control (MAC) control element.

[0021] The method may further include the steps of: the terminal device receiving new configuration information for configuring the transmission of an uplink signal by the terminal device; the terminal device determining that the new configuration information received by the terminal device does not include an indication that the terminal device will use a particular downlink reference signal as a time reference for applying a timing advance value when transmitting an uplink signal; and, in response to the determination that the new configuration information received by the terminal device does not include an indication that the terminal device will use a particular downlink reference signal as a time reference for applying a timing advance value when transmitting an uplink signal, the terminal device determining a time reference according to instructions stored in the terminal device.

[0022] The instruction may indicate that the determination is based on the time of reception of a downlink reference signal associated with one of a set of activated TCI states, where the time reference is detected by the shortest path delay. An activated TCI state in the set of activated TCI states may be associated with a single transmit / receive point TRP, or with a specific set of control resources CORESET, or with a pool index of a specific CORESET.

[0023] In another example, the instruction may indicate that when a terminal device switches from using an initial TCI state to using a new TCI state, the time reference is determined based on the time of reception of the downlink reference signal associated with the initial TCI state.

[0024] In other examples, the instruction may indicate that it is determined based on the time of reception of a reference signal that is indicated to have a spatial relationship with a physical uplink control channel (PUCCH) resource assigned to the terminal device.

[0025] In a fourth aspect, this specification describes a method including the step of a base station transmitting first configuration information including an indication to a terminal device that the terminal device is used as a time reference for the application of a timing advance value when a first downlink reference signal transmits an uplink signal according to a first transmission configuration indicator (TCI) state.

[0026] In some examples, the TCI state configuration information may include the first configuration information. The TCI state configuration information may include a first TCI state configuration corresponding to a first TCI state and a second TCI state configuration corresponding to a second TCI state. The first TCI state configuration includes an indication that the terminal device is used as a time reference for the application of a timing advance value when a first downlink reference signal transmits an uplink signal according to the first TCI state, and the second TCI state configuration includes an indication that the terminal device is used as a time reference for the application of a timing advance value when a first downlink reference signal transmits an uplink signal according to the second TCI state.

[0027] In other examples, the first configuration information can indicate a plurality of TCI states. For the plurality of TCI states, it is used as a time reference for the application of a timing advance value when a first downlink reference signal transmits an uplink signal according to any one of the plurality of TCI states, and the plurality of TCI states includes a first TCI state and a second TCI state.

[0028] The first downlink reference signal may be transmitted using a third beam wider than a first beam associated with the first TCI state and a second beam associated with the second TCI state. The third beam may spatially overlap with the first beam and the second beam.

[0029] The first downlink reference signal can be a synchronization signal block SSB or a channel state information reference signal CSI-RS. The first configuration information can be included in a radio resource control RRC configuration or reconfiguration message, or in a medium access control MAC control element.

[0030] In a fifth aspect, the present specification describes an apparatus (e.g., a terminal device or a component of a terminal device) comprising at least one processor and at least one memory storing instructions, wherein when the instructions are executed by the at least one processor, the apparatus is caused to at least receive first configuration information including an indication that a first downlink reference signal, when transmitting an uplink signal according to a first transmission configuration indicator TCI state, is used by the terminal device as a time reference for the application of a timing advance value; receive the first downlink reference signal; determine a transmission start time for an uplink signal transmitted according to the first TCI state based on the reception time of the first downlink reference signal and the timing advance value; and transmit one or more uplink signals according to the transmission start time and the first TCI state.

[0031] In some examples, the TCI state configuration information may include the first configuration information. The TCI state configuration information can include a first TCI state configuration corresponding to the first TCI state and a second TCI state configuration corresponding to the second TCI state, where the first TCI state configuration includes an indication that the first downlink reference signal is used by the terminal device as a time reference for the application of a timing advance value when transmitting an uplink signal according to the first TCI state, and the second TCI state configuration includes an indication that the first downlink reference signal is used by the terminal device as a time reference for the application of a timing advance value when transmitting an uplink signal according to the second TCI state.

[0032] In other examples, the first configuration information may indicate multiple TCI states, and for the multiple TCI states, the first downlink reference signal is used as a time reference for applying a timing advance value when transmitting an uplink signal according to any of the multiple TCI states, and the multiple TCI states include a first TCI state and a second TCI state.

[0033] The instruction, when executed by at least one processor, can cause the device to switch from transmitting an uplink signal according to a first TCI state to transmitting an uplink signal according to a second TCI state, while at least keeping a first downlink reference signal as a time reference for applying a timing advance value when transmitting an uplink signal according to a second TCI state. The first downlink reference signal may be transmitted using a third beam that is wider than the first beam associated with the first TCI state and the second beam associated with the second TCI state. The third beam may spatially overlap the first and second beams.

[0034] The first downlink reference signal may be a synchronization signal block (SSB) or a channel status information reference signal (CSI-RS). The first configuration information may be contained within a radio resource control (RRC) configuration or reconfiguration message, or within a media access control (MAC) control element.

[0035] When the instruction is executed by at least one processor, it may cause the device to receive new configuration information for configuring the transmission of an uplink signal by a terminal device, to determine that the new configuration information received by the terminal device does not include an indication that a particular downlink reference signal is used by the terminal device as a time reference for applying a timing advance value when transmitting an uplink signal, and, in response to the determination that the new configuration information received by the terminal device does not include an indication that a particular downlink reference signal is used by the terminal device as a time reference for applying a timing advance value when transmitting an uplink signal, to determine the time reference according to additional instructions stored in the terminal device.

[0036] Additional instructions may indicate that the time reference is determined based on the time of reception of a downlink reference signal associated with one of a set of activated TCI states, which are detected by the shortest path delay. An activated TCI state in the set of activated TCI states may be associated with a single transmit / receive point TRP, or with a specific set of control resources CORESET, or with a pool index of a specific CORESET.

[0037] In another example, additional instructions may indicate that when a terminal device switches from using an initial TCI state to using a new TCI state, the time reference is determined based on the time of reception of the downlink reference signal associated with the initial TCI state.

[0038] In other examples, additional instructions may indicate that the time reference is determined based on the time of reception of a reference signal that is indicated to have a spatial relationship with a physical uplink control channel (PUCCH) resource assigned to the terminal device.

[0039] In a sixth embodiment, the Specified Description describes an apparatus (e.g., a component of an apparatus or base station) comprising at least one processor and at least one memory for storing instructions, wherein when an instruction is executed by at least one processor, the apparatus causes the apparatus to transmit to a terminal device first configuration information, which includes at least an indication that a first downlink reference signal is used by a terminal device as a time reference for applying a timing advance value when transmitting an uplink signal according to a first transmit configuration indicator TCI state.

[0040] In some examples, TCI state configuration information may include first configuration information. The TCI state configuration information may include a first TCI state configuration corresponding to a first TCI state and a second TCI state configuration corresponding to a second TCI state, wherein the first TCI state configuration includes an indication that it is used by the terminal device as a time reference for applying a timing advance value when a first downlink reference signal transmits an uplink signal according to the first TCI state, and the second TCI state configuration includes an indication that it is used by the terminal device as a time reference for applying a timing advance value when a first downlink reference signal transmits an uplink signal according to the second TCI state.

[0041] In other examples, the first configuration information may indicate multiple TCI states, and for the multiple TCI states, the first downlink reference signal is used as a time reference for applying a timing advance value when transmitting an uplink signal according to any of the multiple TCI states, and the multiple TCI states include a first TCI state and a second TCI state.

[0042] The first downlink reference signal may be transmitted using a third beam that is wider than the first beam associated with the first TCI state and the second beam associated with the second TCI state. The third beam may spatially overlap the first and second beams.

[0043] The first downlink reference signal may be a synchronization signal block (SSB) or a channel status information reference signal (CSI-RS). The first configuration information may be contained within a radio resource control (RRC) configuration or reconfiguration message, or within a media access control (MAC) control element.

[0044] In a seventh aspect, the Specification describes a terminal device comprising: means for determining the time of reception of a downlink reference signal associated with one of a set of activated TCI states having shortest path delay; means for determining a transmission start time for an uplink signal transmitted according to a first activated TCI state based on the determined reception time and timing advance value; means for receiving the first downlink reference signal; and means for transmitting one or more uplink signals according to the determined transmission start time and the first activated TCI state.

[0045] In an eighth aspect, this specification describes a terminal device comprising: means for switching from transmitting an uplink signal according to an initial (or pre-switch) TCI state to transmitting an uplink signal according to a new TCI state; means for determining a transmission start time for an uplink signal to be transmitted according to the new TCI state based on a timing advance value and the time of reception of a downlink reference signal associated with the initial TCI state; and means for transmitting one or more uplink signals according to the transmission start time and the new TCI state.

[0046] In a ninth aspect, the Specification describes a terminal device comprising: means for determining the time of reception of a reference signal indicated to have a spatial association with a physical uplink control channel PUCCH resource assigned to the terminal device; means for determining the transmission start time for an uplink signal transmitted according to a first activated TCI state based on the determined reception time and timing advance value; means for receiving a first downlink reference signal; and means for transmitting one or more uplink signals according to the transmission start time and the first activated TCI state.

[0047] In a tenth embodiment, this specification describes a non-temporary computer-readable medium that includes program instructions stored thereon to cause the execution of any of the operations described with reference to any of the first to ninth embodiments.

[0048] For a better understanding of this application, references to the attached drawings are made as an example. [Brief explanation of the drawing]

[0049] [Figure 1A] This is a base station with multiple beams that communicate with terminal devices. [Figure 1B] This is a base station with multiple beams that communicate with terminal devices. [Figure 2] This is an example of UL and DL timing when a terminal device switches between two beams. [Figure 3A-3B] This flowchart illustrates various operations that may be performed by base stations and terminal devices according to the examples described herein. [Figure 4] This diagram shows an exemplary configuration of a terminal device that can be configured to perform the various operations described with reference to Figures 1-3. [Figure 5] These are schematic diagrams of exemplary configurations of a base station or TRP that can be configured to perform the various operations described with reference to Figures 1-3. [Figure 6] This is a diagram of a computer-readable medium on which computer-readable code can be stored. [Modes for carrying out the invention]

[0050] In new radio (NR) long-range communication networks, a single base station or transmit / receive point (TRP) (which may be referred to as an NR BS, node B, gNB, 5G node B, or access point) can operate multiple directional beams. Such beamforming improves the link budget for uplink and downlink by increasing antenna gain. This can be particularly beneficial for higher operating bandwidths (e.g., Frequency Range 2, FR2) that experience greater attenuation at larger air interfaces. Beamforming can also help reduce inter-cell interference by concentrating transmissions in a specific direction. For example, using relatively narrow beams can reduce the likelihood of inter-cell interference over a wide range of angles.

[0051] Terminal devices or user equipment (UEs) connected to the TRP can switch between beams. For example, a UE may switch from using the first beam for uplink signals to using the second beam for uplink signals, for example, in response to a network command. Similarly, the TRP may switch between using different beams for downlinks, sometimes without the UE's knowledge.

[0052] Some beams are associated with their respective Channel State Information Reference Signals (CSI-RS), which can be used to evaluate the beams, for example, in precoding matrix indicator (PMI) reporting and / or beam selection filtering. Such beams may be referred to as “CSI-RS beams” below. In addition to CSI-RS beams, NR TRP also operates a broader beam that includes multiple CSI-RS beams. These broader beams carry the synchronization signal block SSB and may therefore be referred to as SSB beams in this specification.

[0053] To enable UEs to configure themselves to receive downlink signals over specific beams and transmit uplink signals over specific beams, the TRP uses radio resource control RRC signaling to transmit configuration indicator (TCI) states to the UEs. These TCI states indicate which parameters the UEs should use when receiving or transmitting signals, by utilizing a concept known as quasi-co-location (QCL). More specifically, for each beam that can be used by the UE, the TCI states indicate which CSI-RS beam or SSB beam each beam is quasi-co-located to. The TCI states indicate the degree of quasi-co-location, i.e., the type of QCL applied. The concept of QCL is known in the art and is therefore not discussed in further detail herein.

[0054] In addition to indicating the associated SSB or CSI reference signal and the associated QCL type, the TCI state includes identification information for the associated cell and bandwidth portion. The TCI state can be an uplink (UL) TCI state, a downlink (DL) TCI state, or a joint uplink and downlink (UL / DL) TCI state. The UL TCI state indicates the parameters to be used when transmitting the uplink signal, the DL TCI state indicates the parameters to be used when receiving the downlink signal, and the joint UL / DL state indicates that the same parameters should be used for both uplink and downlink.

[0055] RRC signaling is used to configure multiple TCI states in the UE (e.g., 128 for physical downlink shared channels (PDSCH) and 64 for physical downlink control channels (PDCCH)). Although the TCI states are configured in the UE, they are deactivated by default after configuration and handover.

[0056] In the case of a PDSCH, one or more of the configured TCI states can then be activated using a control element (CE) of the Media Access Control (MAC) sent to the UE. This can be done by sending a bitmap, where "1" indicates that the TCI state should be activated and "O" indicates that the TCI state should be deactivated. A specific activated TCI state can then be dynamically selected and signaled to the UE. This is done using PDSCH Downlink Control Information (DCI), which can indicate which of the active TCI states are applicable to a particular PDSCH resource allocation. For example, DCI can also indicate which of the activated TCI states the UE should apply to the resource allocation. The UE then uses QCL information from the relevant TCI states to help receive and decode the PDSCH.

[0057] In the case of a PDCCH, MAC CE may be used to activate a single TCI state configured for a specific set of control resources (CORESET). The CORESET defines a set of resource blocks associated with the PDCCH search space. The UE then uses QCL information from the associated TCI state to help decode the PDCCH.

[0058] Therefore, it is understood that the network may use control signals (e.g., MAC-CE or DCI) to cause the UE to switch between different TCI states and between different beam usages.

[0059] Figures 1A and 1B illustrate a scenario in which the terminal device UE1 switches between different beams. In the examples in Figures 1A and 1B, the switching occurs due to the movement of the absorber 10 in the environment. However, it is also understood that the switching may occur from other types of changes in the environment, such as the movement of the reflector or the movement of the terminal device.

[0060] In the examples in Figures 1A and 1B, the transmit / receive point TRP1 operates four narrow beams CSI1-CSI4 and one wider beam SSB1. In the examples, the SSB beam SSB1 is wider than the CSI-RS beams CSI1-CSI4 and overlaps with all of them. The SSB beam SSB1 also has a shorter range than the CSI-RS beams. The beams in Figures 1A and 1B represent the main lobes, but it should be understood that each beam will have associated side lobes that are not shown.

[0061] Graphs 14, 16, and 18, illustrating power delay profiles (PDPs) for the SSB beam, CSI2-RS beam, and CSI3-RS beam, are also shown in Figure 1A. As can be seen, the PDP detected by UE1 when receiving the narrower CSI-RS beam may encompass all channel taps on the main lobe of the SSB beam, while the taps on the main lobe of the narrower CSI-RS beam (indicated by dashed boxes) may be received with higher antenna gain, and other taps from the side lobes and the SSB main lobe may be received with lower antenna gain.

[0062] In Figure 1A, the third CSI-RS beam CSI3 has the shortest path to the terminal device UE1. Therefore, the main lobe of the third CSI-RS beam CSI3 has the maximum power and shortest delay (as seen in PDP18 in Figure 1A). However, due to the presence of a reflector 12 that reflects the main lobe of the second CSI-RS beam CSI2 back toward the terminal device, the main lobe of the second CSI-RS beam CSI2 is also received at a relatively high power (e.g., from PDP16 in Figure 1A), although with a longer delay than the main lobe of the third CSI-RS beam CSI3. The network may be configured to select a UL or joint UL / DL TCI state based on the CSI-RS received at the highest power. Therefore, in the example in Figure 1A, the TCI state associated with (or pseudo-colocated with) the CSI-RS transmitted via the third beam CSI3 may be selected by the network as a UL or joint UL / DL TCI state.

[0063] In Figure 1B, it can be seen that at a later point in time, absorber 10 has moved into the path of the third CSI-RS beam CSI3. Therefore, the third CSI-RS beam is no longer received at maximum power (see 18 in Figure 1B). Instead, the second CSI-RS beam CSI2 is received at maximum power, although it does not have the shortest propagation path (see PDP 16 in Figure 1B). Thus, Figure 1B is understood to be an example of a scenario in which a signal transmitted using a beam with the shortest delay is not received at the strongest power. In Figure 1B, since the second CSI-RS beam CSI2 is now received at maximum power, the network causes the UE to switch to a UL or joint UL / DL TCI state associated with (or pseudo-colocated with) the CSI-RS transmitted via the second beam CSI2.

[0064] As explained above, the propagation path to the terminal device in Figure 1B is different after the TCI state switch (or post-switch), and in this case it is longer than before the TCI state switch (or before the switch) in Figure 1A. To cause the terminal device to transmit the uplink signal at the desired time, the network provides the UE with a timing advance (TA) value. This TA value is to compensate for the propagation path between the terminal device and the TRP. The TA value may be set to double the propagation delay (although this may involve adjustments). The terminal device can use this TA value, along with the time of receiving a reference signal associated with the TCI state, to determine when to start transmitting the uplink signal. However, this TA value may not be updated each time the terminal device switches between UL (or joint) TCI states. For example, if there is no new random access preamble transmission commanded by the network, e.g., the base station, the timing advance value cannot be updated because the TA value is provided in the random access response (RAR). Therefore, the terminal device UE continues to use the existing TA value until a new timing advance command (TAC) is received.

[0065] As mentioned above, the TA value depends on the propagation path delay between the TRP and the terminal device. However, since the propagation delay can differ before and after a UL (or joint) TCI state switch, the difference in propagation delay between the old TCI state and the new TCI state can lead to a shift in the uplink signal transmitted after the switch. A base station may require that all UL signals transmitted by terminal devices using a particular TCI state be received within a specific period, which may be but not limited to one-third of the base station's cyclic prefix (see, for example, 3GPP R1-1707951). In the case of a large propagation delay difference, the difference between the time it takes to receive an uplink signal from a terminal device that has just switched to a new TCI state and the time it takes to receive uplink signals from other terminal devices using that TCI state may be greater than what the base station can tolerate. That is, the uplink signal from the terminal device that just switched may be received outside of the specific period. This can result in inter-symbol interference (ISI) at the base station, which can cause degradation of uplink performance. Furthermore, this can even lead to uplink loss for all terminal devices transmitting in the new TCI state, due to the loss of orthogonality between subcarriers occupied by different terminal devices. In some cases, the base station may not even be able to estimate the uplink timing error and therefore cannot adjust it with a new TAC.

[0066] Implementation of the techniques described herein may prevent or at least reduce instances of such problems that could otherwise arise from TCI state switching.

[0067] In one exemplary embodiment, a network, e.g., a base station / network TRP, provides a terminal device with first configuration information, including an indication of a first downlink reference signal to be used by the terminal device as a time reference for applying a timing advance value when transmitting an uplink signal according to a first TCI state. In other words, the network explicitly indicates to the terminal device a reference signal to be used by the terminal device to determine the timing of the uplink signal. The terminal device then determines the transmit start time for the uplink signal to be transmitted according to the first TCI state, based on the time of reception of the indicated first downlink reference signal and the timing advance value (e.g., previously provided by the base station). The uplink signal is then transmitted according to the transmit start time and the first TCI state.

[0068] By indicating a reference signal to the terminal device that is used to determine the timing of uplink signal transmission using a specific TCI state, it is possible to ensure that the same reference signal is used for multiple active TCI states. In this way, the same reference signal can be used to determine the timing of uplink signals when the terminal device switches between two active TCI states. This can reduce the changes in the propagation delay of the reference signal between the base station and the terminal device that could otherwise result from switching between TCI states, thereby reducing the occurrence of the aforementioned problems, including UL symbol interference in TRP.

[0069] Figure 2 illustrates the beneficial effects of using a common reference signal to determine uplink transmit timing for both the initial (pre-switching) TCI state and the new (post-switching) TCI state. In the example in Figure 2, the first or initial TCI state is associated (or QCL'd) with a reference signal on CSI3, as in Figure 1A, and the second or new TCI state is associated (or QCL'd) with a reference signal on CSI2. In Figure 2, boxes with solid lines represent signals associated with CSI2, and dashed lines represent signals associated with CSI3. Shaded boxes represent uplink signals, and unshaded boxes represent downlink signals.

[0070] Signal (1) represents the transmission time of the DL reference signal from the TRP on the CSI3 beam. Signal (2) represents the transmission time of the DL reference signal from the TRP on the CSI2 beam. In this example, signals (1) and (2) are shown to be transmitted at the same time t0 (or in other words, ideally synchronized).

[0071] Signal (3) represents the time when the CSI3DL reference signal is received by the terminal device. Signal (4) represents the time when the CSI2DL reference signal is received by the terminal device. In this example, the CSI2 beam has a longer propagation path than the CSI3 beam, and therefore the CSI2DL reference signal is received by the terminal device after the CSI3DL reference signal. The CSI3DL reference signal is received with a path delay D1, and the CSI2DL reference signal is received with a path delay of D2. Therefore, the CSI3DL reference signal is received at time t0+D1, and the CSI2DL reference signal is received at time t0+D2.

[0072] Signal (5) represents the timing of the transmission of the uplink UL signal from the terminal device to the TRP. Signal (5) is transmitted before the TCI state switch, and therefore it is sent using the TCI state associated with CSI3. The network provides a timing advance (TA) intended to ensure that the UL signal (5) is received at the TRP as close to t0 as possible. In other words, the timing advance ensures that the signal is received at the TRP at a aligned time. In the ideal situation as illustrated in Figure 2, the timing advance is twice the path delay of the associated reference signal. Thus, in this example, the timing advance is 2 × D1. The terminal device applies a timing advance based on the time of reception of the associated reference signal at the terminal device, which in this case is t1. Therefore, the uplink signal sent over the TCI state associated with CSI3 is sent at time t1 - TA (= t0 - D1).

[0073] Signals (6) and (7) represent a situation after the terminal device has switched from a TCI state associated with CSI3 to a TCI state associated with CSI2, but the approach described herein has not been applied. That is, after the terminal device has switched to a TCI state associated with CSI2, the terminal device uses the CSI2DL reference signal to determine the timing of uplink transmission.

[0074] Signal (6) represents the time of transmission of the uplink signal using the TCI state associated with CSI2. As can be seen, the terminal device applies a TA value based on the time of reception of the CSI2 downlink reference signal (indicated as t2 in Figure 2), which was determined before the switch to the TCI state associated with CSI2 (i.e., a timing advance value determined based on the time of reception of the CSI3DL reference signal). Thus, the start of the transition time for the uplink signal (6) is t2-TA(t0+D2-2D1).

[0075] Signal (7) represents the time of reception of signal (6) at TRP. As can be seen, this is received at time D2 after its transmission time, i.e., at time t0 + 2D2 - 2D1. Therefore, if the signal is ideally received at time t0, the timing error is 2(D2 - D1), where D2 - D1 is the difference in path delay resulting from TCI state switching. As mentioned above, depending on the difference in path delay resulting from TCI state switching, the timing error can produce a number of undesirable effects, in particular ISI.

[0076] Signals (8) and (9) represent a situation where the terminal device has switched from a TCI state associated with CSI3 to a TCI state associated with CSI2, but the approach described herein has been utilized. More specifically, the approach described herein is utilized to ensure that the same DL reference signal is used to determine the UL transmission timing before and after the TCI state switch. In this particular example, the CSI3DL reference signal is used to determine the UL transmission timing before and after the switch to the TCI state associated with CSI2. However, it is understood that different reference signals may be used, as long as the same reference signal is used before and after the TCI state switch. For example, the reference signal may be transmitted over a beam wider than the beams associated with CSI3 and CSI2. The reference signal may be, for example, a synchronization signal block SSB. By using a beam wider than and overlapping with the beams associated with the relevant TCI states, the reference signal is more likely to be received by the terminal device with sufficient intensity over a wider area and therefore more likely to be received by the terminal device when using either of the relevant TCI states.

[0077] Signal (8) represents the transmission time of the uplink signal using the TCI state associated with CSI2. However, in this case, the uplink signal transmission time is determined using the reception time of the CSI3 downlink reference signal. Therefore, the start of UL transmission is t1-TA (=t0-D1).

[0078] Signal (9) represents the time of reception of signal (8) at the TRP. The path delay between the terminal device and the TRP associated with the TCI state associated with CSI2 is D2. Therefore, the time of reception of signal (8) at the TRP is t0 - D1 + D2. Thus, the timing error when using the approach described herein is D2 - D1. It can be understood that this timing error is half the timing error that occurs when determining the uplink transmission timing in the manner described with reference to signals (6) and (7). In other words, when a terminal device switches between different UL TCI states using the approach described herein, it may be possible to switch to a TCI state with a larger propagation delay difference without causing any ISI at the base station compared to when the approach described herein is not applied.

[0079] As described above, in order to enable a common DL reference signal used as an uplink timing reference for multiple TCI states, according to some examples described herein, a terminal device may be provided with first configuration information that includes an indication (e.g., identifier) ​​of a specific downlink reference signal used by the terminal device as a time reference for applying timing advance values ​​when transmitting uplink signals according to a particular TCI state. In some examples, the first configuration information is contained within a TCI state configuration. In this way, the first and second TCI state configurations may each include the same downlink reference signal indication. Therefore, when a terminal device switches between a first TCI state and a second TCI state, it is aware that it uses the same downlink reference signal to determine the UL transmission timing in the second TCI state as it does in the first TCI state.

[0080] As defined separately in 3GPP TS38.331, examples of the first configuration information included in the TCI state configuration are shown below. The first example is for the joint UL / DL TCI state, and the second example is for the UL TCI state. The first configuration information is underlined and shown in bold.

[0081] [Table 1] Example 1 - Joint UL / DL TCI State Configuration

[0082] [Table 2] Example 2 - UL TCI State Configuration

[0083] As can be understood from the above, the “TimingAdvanceRS-Id” field may indicate the identifier of the reference signal (e.g., CSI-RS or SS block) used for terminal devices, UEs, and downlink reference timing when applying the timing advance TA value. It is also understood that this field may have any other name, such as “timingReferenceRS”.

[0084] In other examples, the first configuration information that indicates a specific downlink reference signal used as a time reference for applying timing advance values ​​may not be contained within the TCI state configuration, but rather may refer to multiple TCI states for which the specific downlink reference signal is used. For example, the first configuration information may be contained within an RRC configuration message or reconfiguration message, or within a MAC CE.

[0085] In some cases, indications for specific downlink reference signals used by a terminal device as a time reference for applying timing advance values ​​when transmitting uplink signals may not be provided to the terminal. This may occur, for example, because the provision of such indications is not supported by the base station (or more broadly, the network). In such cases, the terminal device can recognize that the configuration information received by the terminal device does not include such indications and can respond to this by determining the time reference for applying timing advance values ​​when transmitting uplink signals according to the instructions stored in the terminal device. In other cases, for example, if the network is not configured to provide such indications, the terminal device can simply use the instructions stored in the terminal device without any recognition or determination that the configuration information received by the terminal device does not include such indications.

[0086] This instruction may indicate that the timing reference is determined based on the time of reception of a downlink reference signal associated with one of a set of TCI states having the shortest (or minimum) delay. That is, a terminal device can receive CSI reference signals associated with different sets of active TCI states and can identify which CSI reference signal will be received with the minimum delay. The terminal device can then use the CSI reference signal identified as the timing reference for applying the timing advance value when transmitting the uplink signal. The TCI states of the set can be associated with the same TRP, and therefore the actual delay should remain relatively constant even if the identification information of the CSI RS arriving with the minimum delay changes. Thus, as in the example illustrated with reference to Figure 2, the timing error can remain relatively small. As can be understood, the set of TCI states can be any logical set of states, for example, the active TCI states for a terminal device, or it can be associated with a specific set of control resources CORESET, or it can be associated with a pool index of a specific set of control resources CORESET.

[0087] In other examples, the instruction may instead indicate that when the terminal device switches from using the initial (or first) TCI state to using a new (or second) TCI state, the time reference is determined based on the time of reception of the downlink reference signal associated with the initial TCI state. Thus, as in the example in Figure 2, the CSI1 reference signal continues to be used as a timing reference even after the switch to CSI2. In some examples, the terminal may be configured to follow this instruction only if both TCI states (i.e., the initial and new TCI states) are associated with the same CORESET or TRP.

[0088] In yet another example, the instruction may instead indicate that the time reference for the uplink signal is determined based on the time of reception of a reference signal that indicates a spatial association with the physical uplink control channel PUCCH resource assigned to the terminal device. This reference signal may be called a “spatial association reference signal” and may be explicitly indicated to the terminal device. However, in some cases a spatial association reference signal may not be formed, and 3GPP Rel16 specifies that the terminal device should determine the spatial association reference signal as follows: - If a CORESET is configured on a control channel, the TCI state of the CORESET with the lowest ID is used as the spatial association reference signal, or - If CORESET is not configured on the control channel, the active TCI state with the lowest ID applicable to the PDSCH in the active downlink bandwidth portion (DL-BWP) of the control channel is used as the spatially related reference signal.

[0089] Rel16 also introduces default spatial relationships for PUSCH scheduled by DCI format 0_0, where terminal devices determine the spatial relationship reference signal as follows: - If no PUCCH resource is configured on an active UL BWP CC, the default spatial relation reference signal is the TCI state / QCL assumption of the CORESET with the lowest ID. - If no PUCCH resource is configured on an active UL BWP CC in FR2 and RRC connection modes, the default spatial relation reference signal is the TCI state / QCL assumption of the CORESET with the lowest ID.

[0090] In the above, it was explained that these instructions stored in the terminal are applied when it is determined that the terminal is not provided with an indication of a particular downlink reference signal used by the terminal device as a time reference for applying a timing advance value when transmitting an uplink signal. However, it is understood that in other embodiments, the network may not be configured to provide such an indication. In such embodiments, the terminal device may be configured to apply one of the above instructions when determining the uplink timing. In this way, the timing error can be reduced without the signaling overhead associated with providing the terminal device with an indication of a particular downlink reference signal.

[0091] Figures 3A and 3B illustrate various operations that may be performed by a base station or TRP and terminal device according to the embodiments described herein. Specifically, Figure 3A illustrates operations that may be performed by a base station, and Figure 3B illustrates operations that may be performed by a terminal device.

[0092] In operation 3.1, the base station transmits configuration information 30 to the terminal device. As illustrated with reference to some examples described herein, the configuration information 30 may include indications of a specific downlink reference signal used by the terminal device as a time reference for applying timing advance values ​​when transmitting uplink signals according to a particular TCI state. For example, the indications may be included within a TCI state configuration. The terminal device may therefore receive a TCI state configuration for each of a plurality of TCI states, each TCI state configuration including an indication of a specific downlink reference signal.

[0093] In other examples, indications may not be present in the TCI state configuration provided by the base station. In some examples described herein, no indications may be sent at all. In other examples, indications may be sent but not in the TCI state configuration. For example, configuration information 30 may associate multiple TCI states with a specific reference signal used as a timing reference when transmitting uplink signals according to those TCI states. This may reduce signaling overhead but may reduce the flexibility available to the network. It is understood that even if indications for a specific reference signal are not included in the TCI state configuration information, such a TCI state configuration may still be sent to terminal devices.

[0094] In operation 3.2, the terminal device receives configuration information 30.

[0095] In operation 3.3, the terminal device may determine whether the configuration information includes an indication of a specific reference signal used as a timing reference when transmitting the uplink signal. If the indication is included in the configuration information, the terminal device may proceed to operation 3.5. If the indication is not included in the configuration information, the terminal device may proceed to operation 3.6.

[0096] It is naturally understood that in some cases, operation 3.3 may be omitted. For example, if the configuration information always includes such an indication, the terminal device may proceed from operation 3.2 to operation 3.5. Alternatively, if, for example, the network is not configured to provide such an indication, the terminal device may proceed from operation 3.2 to operation 3.6.

[0097] In operation 3.4, the base station transmits various reference signals 32.

[0098] In operation 3.5, the terminal device receives a reference signal 32, which the configuration information indicates will be used as a timing reference when transmitting an uplink signal. The terminal device then proceeds to operation 3.7.

[0099] Alternatively, in operation 3.6, the terminal device receives a reference signal 32 which indicates an instruction stored in the terminal device, to be used as a timing reference when transmitting an uplink signal. Various examples of such instructions are described above with reference to Figure 2. The terminal device then proceeds to operation 3.7.

[0100] In operation 3.7, the terminal device determines the transmission start time for the uplink signal to be transmitted according to the currently selected TCI state, based on the timing advance value and the time of reception of the downlink signal received in the previous operation (i.e., either operation 3.5 or 3.6). This determination is known to those skilled in the art and can be performed as a whole, for example, as described with reference to Figure 2.

[0101] In operation 3.8, the terminal device transmits one or more uplink signals 34 according to the determined transmission start time and the currently selected TCI state. These uplink signals 34 are received by the base station in operation 3.9.

[0102] In operation 3.10, the terminal device switches TCI states. For example, the base station may instruct the terminal device to switch from one active TCI state to another, for example via DCI. After this, the terminal device returns to operation 3.5. Alternatively, if the configuration information did not include indication of a specific reference signal used as a timing reference, the terminal device returns to operation 3.6.

[0103] As part of a TCI state switch, a terminal device may determine a reference signal to be used as a timing reference to determine the uplink timing when transmitting an uplink signal using the new TCI state. This can be determined based on configuration information received in the state of operation 3.2, which may be a TCI state configuration. The reference signal is received in operation 3.5. As described above, the same reference signal may be indicated in both TCI state configurations (i.e., state configuration for the initial TCI state and state configuration for the new TCI state), and thus the timing errors resulting from the TCI state switch can be reduced. Similarly, if the terminal device reverts to operation 3.6 because, for example, the network is not configured to indicate the reference signal used to determine the uplink timing, the instructions stored in the terminal may be configured to utilize a specific reference signal to reduce the timing errors resulting from the TCI state switch, as described above.

[0104] Although not shown in Figure 3, it is understood that a base station, or another base station, may subsequently transmit new configuration information to the terminal device. This new configuration information may be as described above with respect to operations 3.1 and 3.2, but may be determined based on the new context of the terminal device. In some examples, it is understood that the new configuration information may omit such indications, even if the previously received first configuration information contained indications of a particular reference signal used as a timing reference when transmitting the uplink signal. This may occur, for example, if the new configuration information is transmitted by a different base station that does not support transmitting such indications, although this is not exclusive. If this new configuration information is transmitted, the terminal device can return to operation 3.2, where the new configuration information is received, and the process can proceed from there.

[0105] The flowcharts in Figures 3A and 3B are highly simplified and should be understood as merely illustrating the operation of the relevant base station and terminal devices in order to understand the approach described herein. Therefore, it should be understood that various other operations involving base stations and terminal devices are also performed. Such operations are known to those skilled in the art.

[0106] The approach described herein has primarily been explained with reference to switching between states associated with the same base station or TRP. However, it is understood that in some scenarios, this approach may be used to switch between TCI states associated with different TRPs, for example, when two TRPs are associated with a common cell.

[0107] The advantages of the approaches described herein are discussed above, including a reduced ISI. However, it is also understood that the approaches described herein may facilitate the support of terminal devices with multiple active TCI states. According to 3GPP TS38.133, terminal devices are required to maintain accurate time tracking for all TCI states on the active list, otherwise it may not be possible to indicate the selection of a TCI state via DCI without waiting for the next SSB or CSI-RS. However, when the various approaches described herein are used, the UE may not utilize the reference signals associated with each active TCI state to determine uplink timing. Instead, the terminal device may determine uplink timing using only the indicated or subset of the SSBs or CSI-RS associated with the activated TCI states. Section 7.1 of 3GPP TS38.133 (see below) assumes that a terminal device can transmit at the UL with accurate transmission timing only if an SSB exists in the most recent 160ms at FR2-1 (this takes into account clock drift between SSB transmissions and the accuracy of timing detection of the SSB signal). If the terminal device can maintain beam alignment by measuring the CSI reference signal at a frequency of less than 160ms, the UE can monitor the CSI RS for all active TCI states at a much lower frequency than the reference signal used for uplink timing (e.g., wider SSB). As a result, power consumption at the terminal device can be reduced by utilizing the approach described herein. Overhead (such as scheduling constraints) in performing the measurements can also be reduced by using the described approach.

[0108] Mapping to RAN4 requirements As stated above, the various approaches described herein require new RRC signaling (e.g., new fields in TCI state configuration). However, it is also understood that 3GPP RAN4 (Radio Performance and Protocol Modes) requirements may need to be updated to reflect the use of specific reference signals for determining uplink transmit timing. One example of how RAN4 requirements may be updated is shown below with respect to clause 7.1 of 3GPP TS38.133 (which specifies terminal device, UE, and transmit timing requirements). Exemplary updates to the technical specification (TS38.133) are underlined and in bold. It is understood that not all of the updates shown below may be implemented, and different wording may be used.

[0109] [Table 3]

[0110] Exemplary configuration of the device Figure 4 is a schematic diagram of an exemplary configuration of a terminal device UE1 that can be configured to perform the various operations described with reference to Figures 1-3.

[0111] The terminal device UE1 can communicate with, for example, a base station via a suitable radio interface arrangement 805. The interface arrangement 805 may be provided by, for example, a radio section 805-2 (e.g., a transceiver) and an associated antenna arrangement 805-1. The antenna arrangement 805-1 may be located internally or externally to the terminal device UE1. To enable beamforming, the antenna arrangement 805-1 includes multiple antennas. For example, some UEs may include 12 antenna elements, such as four panels, each having four cross-polarized antenna elements.

[0112] The terminal device UE1 includes a controller / control (or processing) device 80 that can operate to control other components of the terminal device UE in addition to performing any suitable combination of operations described in relation to the terminal device UE1 with reference to Figures 1-3. The control device 80 may include a processing unit 801 and a memory 802. Computer-readable code 802-2A can be stored in the memory 802, which, when executed by the processing unit 801, causes the control device 80 to perform any of the operations described herein in relation to the terminal device UE1.

[0113] Exemplary configurations of memory 802 and processing unit 801 are discussed in more detail below.

[0114] Terminal device UE1 could be a device that does not require human interaction, such as an entity related to machine-type communication (MTC). Alternatively, terminal device UE1 could be a device designed for tasks involving human interaction, such as making and receiving phone calls between users, as well as streaming multimedia or providing users with other digital content. Non-limiting examples of terminal device UE1 include smartphones, laptops, smartwatches, tablet computers, e-readers, or vehicle-based terminal devices mounted on cars, buses, unmanned aerial vehicles (UAVs), airplanes, trains, or boats, or any type of terminal device that can be carried by a user or worn by a person.

[0115] If the terminal device UE is a device designed for human interaction, the user may control the operation of the terminal device UE1 by an appropriate user input interface UII 804, such as a keypad, voice commands, a touch-sensitive screen or pad, or a combination thereof. A display 803, speaker, and microphone may also be provided. Furthermore, the terminal device UE1 may have appropriate connectors (either wired or wireless) for connecting to other devices and / or external accessories, such as hands-free devices. The terminal device UE1 may additionally be associated with one or more motion sensors 806 for sensing the movement of the mobile device (e.g., having one, or communicating with one via short-range wired or wireless). The terminal device may additionally include other sensors, such as a GNNS unit.

[0116] Figure 5 is a schematic diagram of an exemplary configuration of a base station or transceiver point TRP1. The base station TRP1 is configured to communicate with a terminal device UE1 via a wireless interface. The base station TRP1 includes a radio frequency antenna array 901 configured to receive and transmit radio frequency signals. Although the base station TRP1 is shown to have an array of four antennas 901, this is merely illustrative. The number of antennas can range from two to several hundred.

[0117] The base station TRP1 further comprises a radio frequency interface circuit mechanism 903 configured to interface between the antenna 901 and the control device 90. The radio frequency interface circuit mechanism 903 may also be known as a transceiver. The base station TRP1 also comprises one or more interfaces 909 through which the base station TRP1 can communicate (for example, via X2 messages) with other base stations and other network entities, such as those of the core network.

[0118] The TRP control device 90 may be configured to process signals from the radio frequency interface circuit mechanism 903, control the radio frequency interface circuit mechanism 903 to generate appropriate RF signals for communicating information to the UE via a wireless communication link, and also exchange information with other network elements via interface 909.

[0119] The TRP control device 90 may include a processing unit 902 and a memory 904. A computer-readable code 904-2A can be stored in the memory 904, which, when executed by the processing unit 902, causes the control device 90 to perform one of the operations assigned to the base station TRP1 described above.

[0120] As should be understood, entities UE1 and TRP1 shown in Figures 4 and 5 above may comprise further elements that are not directly involved with the processing and operation that this application focuses on.

[0121] Some further details of the components and characteristics of the above-mentioned devices / entities / devices UE1, TRP1, and their substitutes are described below.

[0122] The control devices 80 and 90 may comprise processing units 801 and 902 that are communicatively coupled to memories 802 and 904. Memories 802 and 904 have computer-readable instructions 802-2A and 904-2A stored thereon, which, when executed by processing units 801 and 902, cause the control devices 80 and 90 to perform various of the operations described herein. The control devices 80 and 90 may in some cases be referred to as “devices” in general terms.

[0123] The processing units 801 and 902 may be any suitable components and may include one or more processors 801A and 902A of any suitable type or combination of suitable types. For example, the processing units 801 and 902 may be programmable processors that interpret computer program instructions 802-2A and 904-2A and process data. The processing units 801 and 902 may include multiple programmable processors. Alternatively, the processing units 801 and 902 may be programmable hardware, for example, having embedded firmware. The processing units 801 and 902 may be referred to as processing means. The processing units 801 and 902 may, alternatively or additionally, include one or more application-specific integrated circuits (ASICs). In some cases, the processing units 801 and 902 may be referred to as computing devices.

[0124] The processors 801 and 902 are coupled to memory (which may be referred to as one or more storage devices) 802 and 904 and are operable to read data into and write data to / from memory 802 and 904. Memory 802 and 904 may consist of a single memory unit or multiple memory units on which computer-readable instructions (or code) 802-2A and 904-2A are stored. For example, memory 802 and 904 may consist of both volatile memory 802-1 and non-volatile memory 802-2. For example, computer-readable instructions / program code 802-2A and 904-2A can be stored in non-volatile memory 802-2 and 904-2 and executed by processors 801 and 902 using volatile memory 802-1 and 904-1 for temporary storage of data or data and instructions. In some examples, the transmit buffer 802-1B of a terminal device UE may be composed of volatile memory 802-1 of the UE control unit 80. Examples of volatile memory include RAM, DRAM, and SDRAM. Examples of non-volatile memory include ROM, PROM, EEPROM, flash memory, optical storage, and magnetic storage. Memory is sometimes generally referred to as a non-temporary computer-readable memory medium.

[0125] The term "memory" covers memory that includes both non-volatile and volatile memory, and may also cover one or more volatile memory, one or more non-volatile memory, or one or more volatile memory and one or more non-volatile memory.

[0126] Computer-readable instructions / codes 802-2A, 904-2A can be pre-programmed within the control units 80, 90. Alternatively, computer-readable instructions 802-2A, 904-2A can reach the control units 80, 90 via electromagnetic carrier signals, or can be copied from a computer program product, a memory device, or a physical entity 1000 such as a recording medium like a CD-ROM or DVD, as illustrated in Figure 6. Computer-readable instructions 802-2A, 904-2A can provide logic and routines that enable the entity device / device to perform the functions described above. A combination of computer-readable instructions stored in memory (of any of the above types) may be referred to as a computer program product.

[0127] Embodiments of the technology described herein may be implemented as software, hardware, application logic, or a combination of software, hardware, and application logic. The software, application logic, and / or hardware may reside in memory or on any computer medium. In exemplary embodiments, the application logic, software, or set of instructions may be maintained on any one of a variety of conventional computer-readable media. In the context of this document, “memory” or “computer-readable medium” may be any medium or means capable of storing, communicating, propagating, or transporting instructions used by or associated with an instruction execution system, apparatus, or device such as a computer.

[0128] Where appropriate, references to "computer-readable storage media," "computer program products," "computer programs in tangible form," or "processors" or "processing devices" should be understood to include not only computers with different architectures such as single / multiprocessor architectures and sequencer / parallel architectures, but also specialized circuits such as field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), signal processing devices, and other devices. References to computer programs, instructions, and code should be understood to represent software for programmable processor firmware, such as programmable content for hardware devices, as processors for fixed-function devices, gate arrays, programmable logic devices, or as instructions for configured settings or configuration settings.

[0129] Where desired, the different functions discussed herein may be performed in different orders and / or simultaneously. Furthermore, where desired, one or more of the above functions may be optional or combined. Similarly, it should be understood that the flowcharts described herein are merely examples, and the various operations shown therein may be omitted, rearranged, and / or combined.

[0130] Although the methods and apparatus described are related to new radio (NR) networks, it should be understood that they are not limited to such networks and are applicable to various different types of radio networks.

[0131] Various embodiments of the methods and apparatus described herein are presented in independent claims, but other embodiments may include other combinations of features from the described embodiments and / or dependent claims and features from the independent claims, not limited to the combinations expressly presented in the claims.

[0132] While various examples are described above, it should be noted herein that these descriptions should not be taken in an restrictive sense. Rather, there are several variations and modifications that can be made without departing from the scope of the invention as defined in the appended claims.

Claims

1. Terminal device, Means for receiving first configuration information, including an indication that a first downlink reference signal is used by the terminal device as a time reference for applying a timing advance value when transmitting an uplink signal according to a first transmit configuration indicator TCI state, Means for receiving the first downlink reference signal, Means for determining the transmission start time for an uplink signal transmitted according to the first TCI state, based on the reception time of the first downlink reference signal and the timing advance value, Means for transmitting the uplink signal according to the transmission start time and the first TCI state, A terminal device equipped with the following features.

2. The terminal device according to claim 1, wherein the TCI state configuration information includes the first configuration information.

3. The TCI state configuration information includes a first TCI state configuration corresponding to the first TCI state and a second TCI state configuration corresponding to the second TCI state. The first TCI state configuration includes an indication that the first downlink reference signal is used by the terminal device as the time reference for applying the timing advance value when transmitting the uplink signal according to the first TCI state, The terminal device according to claim 2, wherein the second TCI state configuration is used by the terminal device as the time reference for applying the timing advance value when the first downlink reference signal transmits an uplink signal according to the second TCI state.

4. The first configuration information indicates a plurality of TCI states, and the first downlink reference signal is used as the time reference for applying the timing advance value when transmitting an uplink signal according to any TCI state among the plurality of TCI states. The terminal device according to claim 1, wherein the plurality of TCI states include the first TCI state and the second TCI state.

5. The terminal device according to claim 3 or 4, further comprising means for switching from transmitting an uplink signal according to the first TCI state to transmitting an uplink signal according to the second TCI state, while maintaining the first downlink reference signal as the time reference for applying the timing advance value when transmitting an uplink signal according to the second TCI state.

6. The terminal device according to claim 5, wherein the first downlink reference signal is transmitted using a third beam that is wider than the first beam associated with the first TCI state and the second beam associated with the second TCI state.

7. The terminal device according to claim 6, wherein the third beam spatially overlaps with the first beam and the second beam.

8. The terminal device according to any one of claims 1 to 7, wherein the first downlink reference signal is a synchronization signal block SSB.

9. The terminal device according to any one of claims 1 to 7, wherein the first downlink reference signal is a channel state information reference signal CSI-RS.

10. The terminal device according to any one of claims 1 to 9, wherein the first configuration information is included in a wireless resource control RRC configuration or reconfiguration message, or in a media access control MAC control element.

11. Means for receiving new configuration information for configuring the transmission of an uplink signal by the terminal device, Means for determining that the new configuration information received by the terminal device does not include an indication that a particular downlink reference signal is used by the terminal device as a time reference for applying a timing advance value when transmitting an uplink signal, In response to a determination that the new configuration information received by the terminal device does not include an indication that a particular downlink reference signal is used by the terminal device as a time reference for applying a timing advance value when transmitting an uplink signal, means for determining the time reference according to an instruction stored in the terminal device, A terminal device according to any one of claims 1 to 10, further comprising the above.

12. The terminal device according to claim 11, which indicates that the instruction is determined based on the time of reception of a downlink reference signal associated with one of a set of activated TCI states in which the time reference is detected with shortest path delay.

13. The terminal device according to claim 12, wherein the activated TCI state among the set of activated TCI states is associated with a single transmit / receive point TRP, or with a specific set of control resources CORESET, or with a pool index of a specific CORESET.

14. The terminal device according to claim 11, wherein the instruction indicates that when the terminal device switches from using an initial TCI state to using a new TCI state, the time reference is determined based on the time of reception of a downlink reference signal associated with the initial TCI state.

15. The terminal device according to claim 11, wherein the instruction indicates that it is determined based on the time of reception of a reference signal that indicates the time reference has a spatial association with a physical uplink control channel PUCCH resource assigned to the terminal device.

16. A base station comprising means for transmitting first configuration information to a terminal device, including an indication that a first downlink reference signal is used by the terminal device as a time reference for applying a timing advance value when transmitting an uplink signal according to a first transmit configuration indicator TCI state.

17. The base station according to claim 16, wherein the TCI state configuration information includes the first configuration information.

18. The base station according to claim 17, wherein the TCI state configuration information includes a first TCI state configuration corresponding to a first TCI state and a second TCI state configuration corresponding to a second TCI state, the first TCI state configuration includes an indication that the first downlink reference signal is used by the terminal device as the time reference for applying the timing advance value when the first downlink reference signal transmits an uplink signal according to the first TCI state, and the second TCI state configuration includes an indication that the first downlink reference signal is used by the terminal device as the time reference for applying the timing advance value when the first downlink reference signal transmits an uplink signal according to the second TCI state.

19. The base station according to claim 16, wherein the first configuration information indicates a plurality of TCI states, and the first downlink reference signal is used as the time reference for applying the timing advance value when transmitting an uplink signal according to any TCI state among the plurality of TCI states, and the plurality of TCI states include the first TCI state and the second TCI state.

20. The base station according to claim 18 or 19, wherein the first downlink reference signal is transmitted using a third beam that is wider than the first beam associated with the first TCI state and the second beam associated with the second TCI state.

21. The base station according to claim 20, wherein the third beam spatially overlaps with the first beam and the second beam.

22. The base station according to any one of claims 16 to 21, wherein the first downlink reference signal is a synchronization signal block SSB.

23. The base station according to any one of claims 16 to 21, wherein the first downlink reference signal is a channel state information reference signal CSI-RS.

24. The base station according to any one of claims 16 to 21, wherein the first configuration information is included in a wireless resource control RRC configuration or reconfiguration message, or in a media access control MAC control element.

25. The steps include: receiving first configuration information by a terminal device, which includes an indication that a first downlink reference signal is used by the terminal device as a time reference for applying a timing advance value when transmitting an uplink signal according to a first transmit configuration indicator TCI state; The first downlink reference signal is received by the terminal device, The terminal device determines the transmission start time for the uplink signal transmitted according to the first TCI state, based on the reception time and timing advance value of the first downlink reference signal. The steps include: transmitting one or more uplink signals by the terminal device according to the transmission start time and the first TCI state; Methods that include...

26. Steps include: transmitting first configuration information to a terminal device by a base station, including an indication that a first downlink reference signal is used by the terminal device as a time reference for applying a timing advance value when transmitting an uplink signal according to a first transmit configuration indicator (TCI) state. Methods that include...

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