WO2023240405A1

WO2023240405A1 - Methods and apparatuses for multi-trp transmission

Info

Publication number: WO2023240405A1
Application number: PCT/CN2022/098427
Authority: WO
Inventors: Kai Liu
Original assignee: Shenzhen Tcl New Technology Co., Ltd.
Priority date: 2022-06-13
Filing date: 2022-06-13
Publication date: 2023-12-21

Abstract

Methods and apparatuses for multiple-transmission reception point (multi-TRP) transmission are disclosed. The method performed by a user equipment (UE) includes receiving, by the UE, a timing advance (TA) command comprising a first TA value and a second TA value from at least one of a first TRP and a second TRP; updating, by the UE, the first TA value and the second TA value individually or simultaneously; and/or handling or avoiding an overlapping in time domain between uplink signals transmitted to different TRPs by the UE according to a determination of the different TRPs or a determination of the UE.

Description

METHODS AND APPARATUSES FOR MULTI-TRP TRANSMISSION

BACKGROUND OF DISCLOSURE

1. Field of the Disclosure

The present disclosure relates to the field of wireless communication systems, and more particularly, to methods and apparatuses for multiple-transmission reception point (multi-TRP) transmission, for example, the wireless communication systems operating in multiple-input multiple-output (MIMO) systems. More specifically, the target is to provide some solutions to updating two timing advance (TA) values and to avoiding uplink (UL) transmission overlapping in multi-TRP scenario.

2. Description of the Related Art

MIMO is an effective approach to enhance the capacity of a radio link due to the multiplexing of both transmit and receive antennas. MIMO refers to a practical technique for sending and receiving more than one data signal simultaneously over the same radio channel, which improves the performance of spectral efficiency greatly. Progress has been achieved to enable the use of multi-TRP transmission which is one of the key technologies of MIMO in an efficient manner.

In multi-TRP scenario, a user equipment (UE) can receive downlink (DL) signals from different TRPs or transmit uplink (UL) signals to different TRPs. However, different distances from the UE to the different TRPs result in different reception times of the UL signals for the different TRPs. In current specification, each UE maintains only one timing advance (TA) value in spite of multi-TRP. Maintaining only one TA value means that the UE transmitting different UL signals to different TRPs is the same time in advance. UL signal transmission with the same time in advance may lower performance of UL signals due to lower orthogonality with other UL signals transmitted by another UE.

SUMMARY

An object of the present disclosure is to propose methods and apparatuses for multiple-transmission reception point (multi-TRP) transmission.

In a first aspect of the present disclosure, a method for multi-TRP transmission performed by a user equipment (UE) includes receiving, by the UE, a timing advance (TA) command comprising a first TA value and a second TA value from at least one of a first TRP and a second TRP; updating, by the UE, the first TA value and the second TA value individually or simultaneously; and/or handling or avoiding an overlapping in time domain between uplink signals transmitted to different TRPs by the UE according to a determination of the different TRPs or a determination of the UE.

In a second aspect of the present disclosure, a method for multi-TRP transmission performed by a network includes controlling a UE to receive a TA command comprising a first TA value and a second TA value from at least one of a first TRP and a second TRP; controlling the UE to update the first TA value and the second TA value individually or simultaneously; and/or controlling the UE to handle or avoid an overlapping in time domain between uplink signals transmitted to different TRPs by the UE according to a determination of the different TRPs or a determination of the UE.

In a third aspect of the present disclosure, a user equipment (UE) comprises a memory, a transceiver, and a processor coupled to the memory and the transceiver. The processor is configured to perform the above method.

In a fourth aspect of the present disclosure, a network comprises a memory, a transceiver, and a processor coupled to the memory and the transceiver. The processor is configured to perform the above method.

In a fifth aspect of the present disclosure, a non-transitory machine-readable storage medium has stored thereon instructions that, when executed by a computer, cause the computer to perform the above method.

In a sixth aspect of the present disclosure, a chip includes a processor, configured to call and run a computer program stored in a memory, to cause a device in which the chip is installed to execute the above method.

In a seventh aspect of the present disclosure, a computer readable storage medium, in which a computer program is stored, causes a computer to execute the above method.

In an eight aspect of the present disclosure, a computer program product includes a computer program, and the computer program causes a computer to execute the above method.

In a ninth aspect of the present disclosure, a computer program causes a computer to execute the above method.

BRIEF DESCRIPTION OF DRAWINGS

In order to illustrate the embodiments of the present disclosure or related art more clearly, the following figures will be described in the embodiments are briefly introduced. It is obvious that the drawings are merely some embodiments of the present disclosure, a person having ordinary skill in this field can obtain other figures according to these figures without paying the premise.

FIG. 1 is a schematic diagram illustrating an example of a multi-TRP transmission operation according to an embodiment of the present disclosure.

FIG. 2 is a block diagram of one or more user equipments (UEs) and a base station (e.g., gNB) of communication in a communication network system according to an embodiment of the present disclosure.

FIG. 3 is a flowchart illustrating a method for multi-TRP transmission performed by a UE according to an embodiment of the present disclosure.

FIG. 4 is a flowchart illustrating method for multi-TRP transmission by a base station according to an embodiment of the present disclosure.

FIG. 5 is a schematic diagram illustrating an example of updating TA1 and TA2 individually according to an embodiment of the present disclosure.

FIG. 6 is a schematic diagram illustrating an example of updating TA1 and TA2 simultaneously according to an embodiment of the present disclosure.

FIG. 7 is a schematic diagram illustrating an example of a content of MAC CE according to an embodiment of the present disclosure.

FIG. 8 is a schematic diagram illustrating an example of a content of MAC CE according to an embodiment of the present disclosure.

FIG. 9 is a schematic diagram illustrating an example of UL signals from a UE to different TRPs in transmission time according to an embodiment of the present disclosure.

FIG. 10 is a schematic diagram illustrating an example of UL signals from a UE to different TRPs in transmission time according to an embodiment of the present disclosure.

FIG. 11 is a schematic diagram illustrating an example of UL signals from a UE to different TRPs in transmission time according to an embodiment of the present disclosure.

FIG. 12 is a schematic diagram illustrating an example of UL signals from a UE to different TRPs in transmission time according to an embodiment of the present disclosure.

FIG. 13 is a schematic diagram illustrating an example of UL signals from a UE to different TRPs in transmission time according to an embodiment of the present disclosure.

FIG. 14 is a schematic diagram illustrating an example of UL signals from a UE to different TRPs in transmission time according to an embodiment of the present disclosure.

FIG. 15 is a schematic diagram illustrating an example of a report of indication signaling according to an embodiment of the present disclosure.

FIG. 16 is a block diagram of a system for wireless communication according to an embodiment of the present disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the present disclosure are described in detail with the technical matters, structural features, achieved objects, and effects with reference to the accompanying drawings as follows. Specifically, the terminologies in the embodiments of the present disclosure are merely for describing the purpose of the certain embodiment, but not to limit the disclosure.

Multiple-input multiple-output (MIMO) is one of the key technologies in new radio (NR) systems and is successful in commercial deployment. In the communication system of MIMO, both UE and base station comprise of a large number of antenna elements. Especially for base station, these antenna elements can be distributed in different panels, as illustrated in FIG. 1. FIG. 1. illustrates that, in multiple-transmission reception point (multi-TRP) transmission operation, each panel is placed at different position such that the base station can communicate with the UE better. Specifically, panels at different positions are named as multi-TRP in current specification. Both downlink (DL) and uplink (UL) channels can benefit from multi-TRP transmission by leveraging spatial diversity to improve the throughput and reliability of transmission in case of unpredictable blockage between a TRP and a UE especially in a frequency range 2 (FR 2) .

In work-item description (WID) of Release 18, two timing advanced (TA) values are introduced in multi-TRP scenario. Two TA values can let a UE transmit different UL signals to different TRPs with different time in advance. Two TA values can make sure the performance of UL signals. However, two TA values also lead to some issues. The first issue is how to update and distinguish two TA values. The second issue is UL transmission overlapping.

The main idea of some embodiments of the present disclosure is to provide some solutions to updating two TA values and to avoiding UL transmission overlapping. To update 2 TA values, the individual and simultaneous methods are proposed. To indicate 2 TA values, the exemplarily methods to enhance the legacy MAC CE are proposed. To distinguish 2 TA values in enhanced MAC CE, explicit and implicit methods are proposed. To avoid UL transmission overlapping, the exemplarily method of allocating resource properly in time domain for TRP is proposed. Also, to avoid UL transmission overlapping, discard and fallback methods for UE are proposed. Report of indication signaling is proposed to let TRPs know the overlapping event.

FIG. 2 illustrates that, in some embodiments, one or more user equipments (UEs) 10 and a base station (e.g., gNB) 20 (or can be called a network) for communication in a communication network system 40 according to an embodiment of the present disclosure are provided. The communication network system 40 includes the one or more UEs 10 and the base station 20. The one or more UEs 10 may include a memory 12, a transceiver 13, and a processor 11 coupled to the memory 12 and the transceiver 13. The base station 20 may include a memory 22, a transceiver 23, and a processor 21 coupled to the memory 22 and the transceiver 23. The

processor

11 or 21 may be configured to implement proposed functions, procedures and/or methods described in this description. Layers of radio interface protocol may be implemented in the

processor

11 or 21. The

memory

12 or 22 is operatively coupled with the

processor

11 or 21 and stores a variety of information to operate the

processor

11 or 21. The

transceiver

13 or 23 is operatively coupled with the

processor

11 or 21, and the

transceiver

13 or 23 transmits and/or receives a radio signal.

The

processor

11 or 21 may include application-specific integrated circuit (ASIC) , other chipset, logic circuit and/or data processing device. The

memory

12 or 22 may include read-only memory (ROM) , random access memory (RAM) , flash memory, memory card, storage medium and/or other storage device. The

transceiver

13 or 23 may include baseband circuitry to process radio frequency signals. When the embodiments are implemented in software, the techniques described herein can be implemented with modules (e.g., procedures, functions, and so on) that perform the functions described herein. The modules can be stored in the

memory

12 or 22 and executed by the

processor

11 or 21. The

memory

12 or 22 can be implemented within the

processor

11 or 21 or external to the

processor

11 or 21 in which case those can be communicatively coupled to the

processor

11 or 21 via various means as is known in the art.

In some embodiments, the transceiver 13 is configured to receive a timing advance (TA) command comprising a first TA value and a second TA value from at least one of a first TRP and a second TRP, the processor 11 is configured to update the first TA value and the second TA value individually or simultaneously, and/or the processor 11 is configured to handle or avoid an overlapping in time domain between uplink signals transmitted to different TRPs by the transceiver 13 according to a determination of the different TRPs or a determination of the UE 10.

In some embodiments, the processor 21 is configured to control the UE 10 to receive a TA command comprising a first TA value and a second TA value from at least one of a first TRP and a second TRP, the processor 21 is configured to control the UE 10 to update the first TA value and the second TA value individually or simultaneously, and/or the processor 21 is configured to control the UE 10 to handle or avoid an overlapping in time domain between uplink signals transmitted to different TRPs by the transceiver 13 according to a determination of the different TRPs or a determination of the UE 10.

FIG. 3 is a flowchart illustrating a method 300 for multi-TRP transmission performed by a UE according to an embodiment of the present disclosure. In some embodiments, the method 300 for multi-TRP transmission performed by the UE includes: a step 310, receiving, by the UE, a timing advance (TA) command comprising a first TA value and a second TA value from at least one of a first TRP and a second TRP; a step 320, updating, by the UE, the first TA value and the second TA value individually or simultaneously; and/or a step 320, handling or avoiding an overlapping in time domain between uplink signals transmitted to different TRPs by the UE according to a determination of the different TRPs or a determination of the UE.

FIG. 4 is a flowchart illustrating a method 400 for multi-TRP transmission by a base station (or can be called a network) according to an embodiment of the present disclosure. In some embodiments, the method 400 for multi-TRP transmission performed by the network includes: a step 410, controlling a UE to receive a TA command comprising a first TA value and a second TA value from at least one of a first TRP and a second TRP; a step 420, controlling the UE to update the first TA value and the second TA value individually or simultaneously; and/or a step 430, controlling the UE to handle or avoid an overlapping in time domain between uplink signals transmitted to different TRPs by the UE according to a determination of the different TRPs or a determination of the UE.

In some embodiments, the method further comprises receiving, by the UE, a first physical downlink shared channel (PDSCH) carrying the TA command with the first TA value from the first TRP; receiving, by the UE, a second PDSCH carrying the TA command with the second TA value from the second TRP; and updating, by the UE, the first TA value and the second TA value individually when the UE receives the first TA value from the first TRP and the UE receives the second TA value from the second TRP. In some embodiments, the TA command comprises a first field to indicate the first TRP and the second TRP, and the first field comprises a TRP index field, an index of a control resource set (CORESET) pool field, a sounding reference signal (SRS) resource set index field, or a channel state information-reference signal (CSI-RS) resource set index field.

In some embodiments, the method further comprises receiving, by the UE, a first PDSCH carrying the TA command with both the first TA value and the second TA value from the first TRP and updating, by the UE, the first TA value and the second TA value simultaneously when the UE receives both the first TA value and the second TA value from the first TRP. In some embodiments, the TA command comprises a second field to indicate the second TA value. In some embodiments, the TA command comprises a third field to indicate the first TRP and the second TRP, and the third field comprises a TRP index field, an index of a CORESET pool field, an SRS resource set index field, or a CSI-RS resource set index field.

In some embodiments, the TA command is an absolute TA command media access control control element (MAC CE) or a relative TA command MAC CE. In some embodiments, the UE distinguishes a TA value corresponding to the first TRP and a TA value corresponding to the second TRP according to the TRP index filed in the TA command. In some embodiments, the UE distinguishes the first TRP and the second TRP according to a transmission configuration indication (TCI) state information of the first PDSCH or the second PDSCH carrying the TA command or a scrambling sequence information of the first PDSCH or the second PDSCH carrying the TA command.

In some embodiments, for the determination of the different TRPs, an uplink signal resource allocated by a network for the UE satisfies a condition: Δt _P + Δt _Rx + Δt _s > T ₁, where Δt _P= Δt _P1+Δt _P2, Δt _P1 is a signal propagation time from the UE to the first TRP, Δt _P2 is a signal propagation time from the UE to the second TRP, Δt _Rx is a start time difference between a start time of the first TRP receipting a first uplink signal and a start time of the second TRP receipting a second uplink signal, and T ₁ is a duration time of a resource of the first uplink signal.

In some embodiments, for the determination of the UE, if the uplink signals transmitted to the different TRPs by the UE have overlapping in the time domain, the UE chooses one of the uplink signals to transmit to the corresponding TRP. In some embodiments, the UE chooses the one of the uplink signals to transmit to the corresponding TRP according to a time priority rule or an importance priority rule. In some embodiments, for the time priority rule, if a transmission time of a first uplink signal corresponding to the first TRP is earlier than a transmission time of a second uplink signal corresponding to the second TRP, the UE chooses the first uplink signal to transmit to the first TRP with the first TA value and does not transmit the second uplink signal. In some embodiments, for the importance priority rule, if a first uplink signal corresponding to the first TRP is more important than a second uplink signal corresponding to the second TRP, the UE chooses the first uplink signal to transmit to the first TRP with the first TA value and does not transmit the second uplink signal.

In some embodiments, for the determination of the UE, if the uplink signals transmitted to the different TRPs by the UE have overlapping in the time domain, the UE chooses one of the uplink signals to transmit to the corresponding TRP with the corresponding TA value and transmit a segment of another uplink signal to another TRP with another TA value. In some embodiments, the UE choosing one of the signals to be truncated follows a time priority rule or an importance priority rule. In some embodiments, if both a first uplink signal and a second uplink signal are PUSCHs with data, the UE transmits a segment of the first uplink signal to the first TRP with the first TA value and transmits a whole of the second uplink signal to the second TRP with the second TA value.

In some embodiments, for the determination of the UE, if the uplink signals transmitted to the different TRPs by the UE have overlapping in the time domain, the UE puts information carried by one of the uplink signals into another uplink signal and transmits the uplink signal with combined information to one of TRPs with a corresponding TA value. In some embodiments, if a first uplink signal and a second uplink signal are a PUSCH with data and a PUCCH with HARQ, the UE put a HARQ information into a data information and transmits the first uplink signal to the first TRP with the first TA value.

In some embodiments, for the determination of the UE, if the uplink signals transmitted to the different TRPs by the UE have overlapping but received by different TRPs do not have overlapping in the time domain, the UE is back to a current mode of multi-TRP with one TA value. In some embodiments, if there is overlapping in the time domain, the UE transmits a first uplink signal to the first TRP with the first TA value, then transmits a second uplink signal to the second TRP also with the first TA value.

In some embodiments, if the UE is aware of an overlapping of transmission time of the uplink signals for the different TRPs, the UE reports an indication signaling to a network. In some embodiments, after the UE uses a discard method or a fallback method to transmit the uplink signal, the UE reports the indication signaling to the network. In some embodiments, the indication signaling is an MAC CE providing a difference between the first TA value and the second value or a TRP indication. In some embodiments, to report the indication signaling, the UE needs to transmit a PUCCH with a scheduling request to the network. In some embodiments, a specific configuration of the scheduling request is provided by the network for the UE to report the indication signaling.

In current specification, an absolute timing advance command MAC CE, included in a random access response (such as message 2 (msg2) ) , is used to indicate an absolute TA value of PUSCH scheduled by RAR UL grant (such as msg3) when the UE is in the random access procedure. When the UE is in a connection mode, the timing advance command MAC CE is used to indicate a relative TA value of UL signal transmission. In these two types of MAC CEs, the timing advance command filed can indicate only 1 TA. For the case of multi-TRP with 2 TAs, there are two methods to update TA values.

FIG. 5 is a schematic diagram illustrating an example of updating TA1 and TA2 individually according to an embodiment of the present disclosure. FIG. 5 illustrates that, in some embodiments, the first exemplarily method is that TA1 and TA2 update individually. For example, as illustrated in FIG. 5, TRP1 transmits PDSCH1 carrying timing advance command MAC CE with TA1 value and TRP2 transmits PDSCH2 carrying timing advance command MAC CE with TA2 value, respectively. When the UE receives the MAC CE (s) , the UE updates two TA values individually.

FIG. 6 is a schematic diagram illustrating an example of updating TA1 and TA2 simultaneously according to an embodiment of the present disclosure. FIG. 6 illustrates that, in some embodiments, the second exemplarily method is that TA1 and TA2 update simultaneously. For example, as illustrated in FIG. 6, TRP1 transmits PDSCH1 carrying timing advance command MAC CE with both TA1 and TA2 values. When the UE receives the MAC CE (s) , the UE updates two TA values simultaneously. In another embodiment, TRP2 transmits PDSCH2 carrying timing advance command MAC CE with both TA1 and TA2 values. When the UE receives the MAC CE (s) , the UE updates two TA values simultaneously.

FIG. 7 is a schematic diagram illustrating an example of a content of MAC CE according to an embodiment of the present disclosure. FIG. 7 illustrates that, in some embodiments, for the first exemplarily method of updating 2 TAs, both the absolute timing advance command MAC CE and the relative timing advance command MAC CE in the current specification can be reused for updating 2 TA values. On the other hand, a new filed can be added in these two MAC CEs to indicate TRP explicitly. This new filed can be such as an explicit TRP index, an index of a CORESET pool, an SRS resource set index, a CSI-RS resource set index. FIG. 7 shows an example of the new timing advance command MAC CE.

FIG. 8 is a schematic diagram illustrating an example of a content of MAC CE according to an embodiment of the present disclosure. FIG. 8 illustrates that, in some embodiments, for the second exemplarily method, the absolute timing advance command MAC CE and the relative timing advance command MAC CE need to enhance based on the current specification. The first way is to add a new filed to indicate the second TA value. FIG. 8 (a) shows an example of the first way. The second way is to add a new filed to indicate TRP explicitly based on the first way. This new filed can be such as the explicit TRP index, the index of the CORESET pool, the SRS resource set index, the CSI-RS resource set index. FIG. 8 (b) shows an example of the second way.

After the UE receives the absolute timing advance command MAC CE and the relative timing advance command MAC CE, the UE needs to distinguish which TA belongs to which TRP. There are explicit and implicit ways for the UE to distinguish. For the explicit way, the UE can distinguish which TRP belongs to according to the TRP index filed in the MAC CE. For the implicit way, the UE can distinguish which TRP belongs to according to the TCI state information of PDSCH carrying MAC CE, the scrambling sequence information of PDSCH carrying MAC CE.

In current specification, because of 1 TA, the UE transmitting UL signals to different TRPs has the same time in advance. In this case, UL signals from the UE to different TRPs in transmission time do not overlap. However, after introducing 2 TAs, the UE transmitting UL signals to different TRPs has the different time in advance. In this case, UL signals from the UE to different TRPs in transmission time may overlap. For the UE with single transmit (Tx) , it cannot transmit UL signals simultaneously. Also, for multi-panel UE with simultaneous Tx, the Rel-18 WID forbids that the UE transmits different UL channels simultaneously, for example, PUSCH plus PUCCH. Therefore, there are some methods proposed to avoid or handle with the overlapping situation.

FIG. 9 is a schematic diagram illustrating an example of UL signals from a UE to different TRPs in transmission time according to an embodiment of the present disclosure. FIG. 9 illustrates that, in some embodiments, FIG. 9 (a) shows the case of 1 TA and FIG. 9 (b) shows the case of 2 TAs. UL signal 1 is transmitted from the UE to TRP1 and UL signal 2 is transmitted from the UE to TRP2, respectively. There is not overlapping in time domain when TRP1 receive UL signal 1 and TRP2 receive UL signal 2. In the case of 1 TA, the UE can transmit UL signal 1 and UL signal 2 in turn. Hence, there is not overlapping in time domain when the UE transmits

UL signal

1 and 2. However, in the case of 2 TAs, assuming that TA2 is greater than TA1, the UE needs to transmit UL signal 2 more in advance. Hence, there is overlapping in time domain when the UE transmits UL signal 1 and UL signal 2.

FIG. 10 is a schematic diagram illustrating an example of UL signals from a UE to different TRPs in transmission time according to an embodiment of the present disclosure. FIG. 10 illustrates that, in some embodiments, if the time difference Δt _Tx between the start time of the UE transmitting the UL signal 1 and the UE transmitting the UL signal 2 is larger than the duration time T ₁ of UL signal 1 resource, the transmission time of UL signal 1 and the transmission time of UL signal 2 do not overlap. According to the analysis, the formula t _P1 + Δt _Tx = t _P2 + Δt _Rx is workable, where t _P1 is the signal propagation time from UE to TRP1, t _P2 is the signal propagation time from UE to TRP2, and Δt _Rx is the start time difference between the start time of TRP1 receipting UL signal 1 and TRP2 receipting UL signal 2. Then, Δt _Tx = (t _P2 -t _P1) + Δt _Rx = Δt _P + Δt _Rx. Therefore, if Δt _P + Δt _Rx > T ₁, the transmission time of UL signal 1 and the transmission time of UL signal 2 do not overlap. In some embodiments, switching time between different beams for UE needs to be considered. Therefore, the condition of non-overlapping becomes Δt _P + Δt _Rx + Δt _s > T ₁. Generally, the signal propagation time is related to the TA value. For example, the signal propagation time is half of the TA value according to the definition of long term evolution (LTE) and NR.

For network, the signal propagation time is dependent on the measurement of previous UL signal (s) , such as PRACH, SRS, and so on. The switching time of different beams is dependent on UE capability. The duration time of UL signal and the reception time difference between different UL signals are dependent on the resource allocation by the network. Hence, if the network knowns these parameters in the above-mentioned condition, the overlapping can be avoided. It is proposed that the overlapping between signals that UE transmits to difference TRPs can be avoided by the network allocating an UL signal resource for the UE properly to satisfy the condition: Δt _P + Δt _Rx + Δt _s > T ₁.

In some embodiments, one of TRPs may not know a TA value from the UE to the other TRP and one of TRPs may not predict the reception time of a UL signal from the UE to the other TRP. Hence, it is needed for the UE to determine how to transmit UL signals to different TRPs.

FIG. 11 is a schematic diagram illustrating an example of UL signals from a UE to different TRPs in transmission time according to an embodiment of the present disclosure. FIG. 11 illustrates that, for exemplary whole discard method, in some embodiments, if UL signals transmitted to different TRPs by the UE have overlapping in time domain, the UE can choose one of signals to transmit to the corresponding TRP according to some rules, for example, time priority rule or importance priority rule. For time priority rule, as shown in FIG 11 (a) , if both UL signal 1 and UL signal 2 are PUSCHs with data and the transmission time of UL signal 1 is earlier than that of UL signal 2, the UE chooses UL signal 1 to transmit to TRP1 with TA1 and does not transmit UL signal 2 to TRP2. For importance priority rule, as shown in FIG. 11 (b) , if UL signal 1 is PUSCH with data and UL signal 2 is PUCCH with HARQ, UE chooses UL signal 2 to transmit to TRP2 with TA2 and does not transmit UL signal 1 to TRP1.

FIG. 12 is a schematic diagram illustrating an example of UL signals from a UE to different TRPs in transmission time according to an embodiment of the present disclosure. FIG. 12 illustrates that, in some embodiments, if UL signals transmitted to different TRPs by the UE have overlapping in time domain, the UE can choose one of signals to transmit to the corresponding TRP and transmit a segment of another UL signal to another TRP. Choosing which signal to be truncated can also follow time priority rule or importance priority rule. For example, for exemplary segmental discard method, as shown in FIG. 12, if both UL signal 1 and UL signal 2 are PUSCHs with data, the UE can transmit segmental UL signal 1 to TRP1 with TA1 and transmit whole UL signal 2 to TRP2 with TA2. It should be explained that the truncated signal is UL signal 1 instead of UL signal 2 because DMRS is more important than data at the overlapping PUSCH in time domain.

FIG. 13 is a schematic diagram illustrating an example of UL signals from a UE to different TRPs in transmission time according to an embodiment of the present disclosure. FIG. 13 illustrates that, in some embodiments, if UL signals transmitted to different TRPs by the UE have overlapping in time domain, the UE can put information carried by one of UL signals into another UL signal and transmit the UL signal with combined information to one of TRPs with corresponding TA. For example, for exemplary merger method, as shown in FIG. 13, if UL signal 1 and UL signal 2 are PUSCHs with data and PUCCH with HARQ (maybe 2 bits) , the UE can put HARQ information into data information and transmit UL signal 1 to TRP1 with TA1.

FIG. 14 is a schematic diagram illustrating an example of UL signals from a UE to different TRPs in transmission time according to an embodiment of the present disclosure. FIG. 10 illustrates that, for exemplary fallback method, in some embodiments, if UL signals transmitted to different TRPs by the UE have overlapping but received by different TRPs do not have overlapping in time domain, the UE can back to the current specification mode, that is, multi-TRP with 1 TA. For example, as shown in FIG. 14, if there is overlapping in time domain, the UE can transmit UL signal 1 to TRP1 with TA1, then transmit UL signal 2 to TRP2 also with TA1. Although this mechanism lowers the receiving performance of UL signal 2, the resource of UL signal 2 is not waste. That means this exemplary method can save time-frequency resource.

FIG. 15 is a schematic diagram illustrating an example of a report of indication signaling according to an embodiment of the present disclosure. FIG. 15 illustrates that, in some embodiments, if the UE is aware of that the overlapping of transmission time of UL signals for different TRPs, the UE can report an indication signaling to the network. After the UE uses the discard or fallback method to transmit the UL signal, the UE can also report an indication signaling to the network. This indication signaling can let the network know the resource allocation in time domain is not reasonable. Moreover, its content may be a MAC CE providing the difference between two TA values. FIG. 15 shows an example of the MAC CE. The R filed can contain other information, such as TRP indication. To report this indication signaling, the UE needs to transmit PUCCH with a scheduling request to the network. Therefore, it is proposed that the network needs to provide a specific configuration of a scheduling request for the UE to report this indication signaling.

In summary, some embodiments of the present disclosure provide some solutions to updating two TA values and to avoiding UL transmission overlapping. To update 2 TA values, the individual and simultaneous methods are proposed. To indicate 2 TA values, the exemplarily methods to enhance the legacy MAC CE are proposed. To distinguish 2 TA values in enhanced MAC CE, explicit and implicit methods are proposed. To avoid UL transmission overlapping, the exemplarily method of allocating resource properly in time domain for TRP is proposed. Also, to avoid UL transmission overlapping, discard and fallback methods for UE are proposed. Report of indication signaling is proposed to let TRPs know the overlapping event. The beneficial effects of some embodiments of the present disclose include at least one of the followings: 1. Introducing individual and simultaneous update two TA values. 2. Enhancing MAC CE to indicate two TA values. 3. Introducing explicit and implicit methods to distinguish two TA values from MAC CE. 4. Introducing a resource allocation method for TRP to avoid UL transmission overlapping. 5. Introducing whole discard, segmental discard, merger, and/or fallback methods for the UE to avoid UL transmission overlapping. 6. Introducing a report mechanism such that the UE can report an overlapping event to TRPs.

FIG. 16 is a block diagram of an example system 700 for wireless communication according to an embodiment of the present disclosure. Embodiments described herein may be implemented into the system using any suitably configured hardware and/or software. FIG. 16 illustrates the system 700 including a radio frequency (RF) circuitry 710, a baseband circuitry 720, an application circuitry 730, a memory/storage 740, a display 750, a camera 760, a sensor 770, and an input/output (I/O) interface 780, coupled with each other at least as illustrated. The application circuitry 730 may include a circuitry such as, but not limited to, one or more single-core or multi-core processors. The processors may include any combination of general-purpose processors and dedicated processors, such as graphics processors, application processors. The processors may be coupled with the memory/storage and configured to execute instructions stored in the memory/storage to enable various applications and/or operating systems running on the system.

While the present disclosure has been described in connection with what is considered the most practical and preferred embodiments, it is understood that the present disclosure is not limited to the disclosed embodiments but is intended to cover various arrangements made without departing from the scope of the broadest interpretation of the appended claims.

Claims

A method for multiple-transmission reception point (multi-TRP) transmission performed by a user equipment (UE) , comprising:

receiving, by the UE, a timing advance (TA) command comprising a first TA value and a second TA value from at least one of a first TRP and a second TRP;

updating, by the UE, the first TA value and the second TA value individually or simultaneously; and/or

handling or avoiding an overlapping in time domain between uplink signals transmitted to different TRPs by the UE according to a determination of the different TRPs or a determination of the UE.
The method according to claim 1, further comprising:

receiving, by the UE, a first physical downlink shared channel (PDSCH) carrying the TA command with the first TA value from the first TRP;

receiving, by the UE, a second PDSCH carrying the TA command with the second TA value from the second TRP; and

updating, by the UE, the first TA value and the second TA value individually when the UE receives the first TA value from the first TRP and the UE receives the second TA value from the second TRP.
The method according to claim 1 or 2, wherein the TA command comprises a first field to indicate the first TRP and the second TRP, and the first field comprises a TRP index field, an index of a control resource set (CORESET) pool field, a sounding reference signal (SRS) resource set index field, or a channel state information-reference signal (CSI-RS) resource set index field.
The method according to claim 1, further comprising:

receiving, by the UE, a first PDSCH carrying the TA command with both the first TA value and the second TA value from the first TRP; and

updating, by the UE, the first TA value and the second TA value simultaneously when the UE receives both the first TA value and the second TA value from the first TRP.
The method according to claim 4, wherein the TA command comprises a second field to indicate the second TA value.
The method according to claim 5, wherein the TA command comprises a third field to indicate the first TRP and the second TRP, and the third field comprises a TRP index field, an index of a CORESET pool field, an SRS resource set index field, or a CSI-RS resource set index field.
The method according to any one of claims 1 to 6, wherein the TA command is an absolute TA command media access control control element (MAC CE) or a relative TA command MAC CE.
The method according to claim 3 or 6, wherein the UE distinguishes a TA value corresponding to the first TRP and a TA value corresponding to the second TRP according to the TRP index filed in the TA command.
The method according to any one of claims 3 to 8, wherein the UE distinguishes the first TRP and the second TRP according to a transmission configuration indication (TCI) state information of the first PDSCH or the second PDSCH carrying the TA command or a scrambling sequence information of the first PDSCH or the second PDSCH carrying the TA command.
The method according to any one of claims 1 to 9, wherein for the determination of the different TRPs, an uplink signal resource allocated by a network for the UE satisfies a condition: Δt _P + Δt _Rx + Δt _s >T ₁, where Δt _P= Δt _P1+Δt _P2, Δt _P1 is a signal propagation time from the UE to the first TRP, Δt _P2 is a signal propagation time from the UE to the second TRP, Δt _Rx is a start time difference between a start time of the first TRP receipting a first uplink signal and a start time of the second TRP receipting a second uplink signal, and T ₁ is a duration time of a resource of the first uplink signal.
The method according to any one of claims 1 to 9, wherein for the determination of the UE, if the uplink signals transmitted to the different TRPs by the UE have overlapping in the time domain, the UE chooses one of the uplink signals to transmit to the corresponding TRP.
The method according to claim 11, wherein the UE chooses the one of the uplink signals to transmit to the corresponding TRP according to a time priority rule or an importance priority rule.
The method according to claim 12, wherein for the time priority rule, if a transmission time of a first uplink signal corresponding to the first TRP is earlier than a transmission time of a second uplink signal corresponding to the second TRP, the UE chooses the first uplink signal to transmit to the first TRP with the first TA value and does not transmit the second uplink signal.
The method according to claim 12, wherein for the importance priority rule, if a first uplink signal corresponding to the first TRP is more important than a second uplink signal corresponding to the second TRP, the UE chooses the first uplink signal to transmit to the first TRP with the first TA value and does not transmit the second uplink signal.
The method according to any one of claims 1 to 9, wherein for the determination of the UE, if the uplink signals transmitted to the different TRPs by the UE have overlapping in the time domain, the UE chooses one of the uplink signals to transmit to the corresponding TRP with the corresponding TA value and transmit a segment of another uplink signal to another TRP with another TA value.
The method according to claim 15, wherein the UE choosing one of the signals to be truncated follows a time priority rule or an importance priority rule.
The method according to claim 15 or 16, wherein if both a first uplink signal and a second uplink signal are PUSCHs with data, the UE transmits a segment of the first uplink signal to the first TRP with the first TA value and transmits a whole of the second uplink signal to the second TRP with the second TA value.
The method according to any one of claims 1 to 9, wherein for the determination of the UE, if the uplink signals transmitted to the different TRPs by the UE have overlapping in the time domain, the UE puts information carried by one of the uplink signals into another uplink signal and transmits the uplink signal with combined information to one of TRPs with a corresponding TA value.
The method according to claim 18, wherein if a first uplink signal and a second uplink signal are a PUSCH with data and a PUCCH with HARQ, the UE put a HARQ information into a data information and transmits the first uplink signal to the first TRP with the first TA value.
The method according to any one of claims 1 to 9, wherein for the determination of the UE, if the uplink signals transmitted to the different TRPs by the UE have overlapping but received by different TRPs do not have overlapping in the time domain, the UE is back to a current mode of multi-TRP with one TA value.
The method according to claim 20, wherein if there is overlapping in the time domain, the UE transmits a first uplink signal to the first TRP with the first TA value, then transmits a second uplink signal to the second TRP also with the first TA value.
The method according to any one of claims 1 to 21, wherein if the UE is aware of an overlapping of transmission time of the uplink signals for the different TRPs, the UE reports an indication signaling to a network.
The method according to claim 22, wherein after the UE uses a discard method or a fallback method to transmit the uplink signal, the UE reports the indication signaling to the network.
The method according to claim 22 or 23, wherein the indication signaling is an MAC CE providing a difference between the first TA value and the second value or a TRP indication.
The method according to any one of claims 22 to 24, wherein to report the indication signaling, the UE needs to transmit a PUCCH with a scheduling request to the network.
The method according to claim 24, wherein a specific configuration of the scheduling request is provided by the network for the UE to report the indication signaling.
A method for multi-TRP transmission performed by a network, comprising:

controlling a UE to receive a TA command comprising a first TA value and a second TA value from at least one of a first TRP and a second TRP;

controlling the UE to update the first TA value and the second TA value individually or simultaneously; and/or

controlling the UE to handle or avoid an overlapping in time domain between uplink signals transmitted to different TRPs by the UE according to a determination of the different TRPs or a determination of the UE.
A user equipment, comprising:

a memory;

a transceiver; and

a processor coupled to the memory and the transceiver;

wherein the processor is configured to execute the method of any one of claims 1 to 26.
A network, comprising:

a memory;

a transceiver; and

a processor coupled to the memory and the transceiver;

wherein the processor is configured to execute the method of claim 27.
A non-transitory machine-readable storage medium having stored thereon instructions that, when executed by a computer, cause the computer to perform the method of any one of claims 1 to 27.
A chip, comprising:

a processor, configured to call and run a computer program stored in a memory, to cause a device in which the chip is installed to execute the method of any one of claims 1 to 27.
A computer readable storage medium, in which a computer program is stored, wherein the computer program causes a computer to execute the method of any one of claims 1 to 27.
A computer program product, comprising a computer program, wherein the computer program causes a computer to execute the method of any one of claims 1 to 27.
A computer program, wherein the computer program causes a computer to execute the method of any one of claims 1 to 27.